Struct clap::builder::Arg

pub struct Arg { /* private fields */ }

The abstract representation of a command line argument. Used to set all the options and relationships that define a valid argument for the program.

There are two methods for constructing Args, using the builder pattern and setting options manually, or using a usage string which is far less verbose but has fewer options. You can also use a combination of the two methods to achieve the best of both worlds.

• Basic API
• Value Handling
• Help
• Advanced Argument Relations
• Reflection

Examples

// Using the traditional builder pattern and setting each option manually
let cfg = Arg::new("config")
      .short('c')
      .long("config")
      .action(ArgAction::Set)
      .value_name("FILE")
      .help("Provides a config file to myprog");
// Using a usage string (setting a similar argument to the one above)
let input = arg!(-i --input <FILE> "Provides an input file to the program");

Implementations

impl Arg

Basic API

pub fn new(id: impl Into<Id>) -> Self

Create a new Arg with a unique name.

The name is used to check whether or not the argument was used at runtime, get values, set relationships with other args, etc..

NOTE: In the case of arguments that take values (i.e. Arg::action(ArgAction::Set)) and positional arguments (i.e. those without a preceding - or --) the name will also be displayed when the user prints the usage/help information of the program.

Examples

Arg::new("config")

Examples found in repository

src/builder/command.rs (line 4240)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn id(self, id: impl Into<Id>) -> Self

Set the identifier used for referencing this argument in the clap API.

See Arg::new for more details.

Examples found in repository

src/builder/arg.rs (line 108)

    pub fn new(id: impl Into<Id>) -> Self {
        Arg::default().id(id)
    }

pub fn short(self, s: impl IntoResettable<char>) -> Self

Sets the short version of the argument without the preceding -.

By default V and h are used by the auto-generated version and help arguments, respectively. You will need to disable the auto-generated flags (disable_help_flag, disable_version_flag) and define your own.

Examples

When calling short, use a single valid UTF-8 character which will allow using the argument via a single hyphen (-) such as -c:

let m = Command::new("prog")
    .arg(Arg::new("config")
        .short('c')
        .action(ArgAction::Set))
    .get_matches_from(vec![
        "prog", "-c", "file.toml"
    ]);

assert_eq!(m.get_one::<String>("config").map(String::as_str), Some("file.toml"));

To use -h for your own flag and still have help:

let m = Command::new("prog")
    .disable_help_flag(true)
    .arg(Arg::new("host")
        .short('h')
        .long("host"))
    .arg(Arg::new("help")
        .long("help")
        .global(true)
        .action(ArgAction::Help))
    .get_matches_from(vec![
        "prog", "-h", "wikipedia.org"
    ]);

assert_eq!(m.get_one::<String>("host").map(String::as_str), Some("wikipedia.org"));

Examples found in repository

src/builder/command.rs (line 4241)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn long(self, l: impl IntoResettable<Str>) -> Self

Sets the long version of the argument without the preceding --.

By default version and help are used by the auto-generated version and help arguments, respectively. You may use the word version or help for the long form of your own arguments, in which case clap simply will not assign those to the auto-generated version or help arguments.

NOTE: Any leading - characters will be stripped

Examples

To set long use a word containing valid UTF-8. If you supply a double leading -- such as --config they will be stripped. Hyphens in the middle of the word, however, will not be stripped (i.e. config-file is allowed).

Setting long allows using the argument via a double hyphen (--) such as --config

let m = Command::new("prog")
    .arg(Arg::new("cfg")
        .long("config")
        .action(ArgAction::Set))
    .get_matches_from(vec![
        "prog", "--config", "file.toml"
    ]);

assert_eq!(m.get_one::<String>("cfg").map(String::as_str), Some("file.toml"));

Examples found in repository

src/builder/command.rs (line 4242)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn alias(self, name: impl IntoResettable<Str>) -> Self

Add an alias, which functions as a hidden long flag.

This is more efficient, and easier than creating multiple hidden arguments as one only needs to check for the existence of this command, and not all variants.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
            .long("test")
            .alias("alias")
            .action(ArgAction::Set))
       .get_matches_from(vec![
            "prog", "--alias", "cool"
        ]);
assert_eq!(m.get_one::<String>("test").unwrap(), "cool");

pub fn short_alias(self, name: impl IntoResettable<char>) -> Self

Add an alias, which functions as a hidden short flag.

This is more efficient, and easier than creating multiple hidden arguments as one only needs to check for the existence of this command, and not all variants.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
            .short('t')
            .short_alias('e')
            .action(ArgAction::Set))
       .get_matches_from(vec![
            "prog", "-e", "cool"
        ]);
assert_eq!(m.get_one::<String>("test").unwrap(), "cool");

pub fn aliases(self, names: impl IntoIterator<Item = impl Into<Str>>) -> Self

Add aliases, which function as hidden long flags.

This is more efficient, and easier than creating multiple hidden subcommands as one only needs to check for the existence of this command, and not all variants.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                    .long("test")
                    .aliases(["do-stuff", "do-tests", "tests"])
                    .action(ArgAction::SetTrue)
                    .help("the file to add")
                    .required(false))
            .get_matches_from(vec![
                "prog", "--do-tests"
            ]);
assert_eq!(*m.get_one::<bool>("test").expect("defaulted by clap"), true);

pub fn short_aliases(self, names: impl IntoIterator<Item = char>) -> Self

Add aliases, which functions as a hidden short flag.

This is more efficient, and easier than creating multiple hidden subcommands as one only needs to check for the existence of this command, and not all variants.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                    .short('t')
                    .short_aliases(['e', 's'])
                    .action(ArgAction::SetTrue)
                    .help("the file to add")
                    .required(false))
            .get_matches_from(vec![
                "prog", "-s"
            ]);
assert_eq!(*m.get_one::<bool>("test").expect("defaulted by clap"), true);

pub fn visible_alias(self, name: impl IntoResettable<Str>) -> Self

Add an alias, which functions as a visible long flag.

Like Arg::alias, except that they are visible inside the help message.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                .visible_alias("something-awesome")
                .long("test")
                .action(ArgAction::Set))
       .get_matches_from(vec![
            "prog", "--something-awesome", "coffee"
        ]);
assert_eq!(m.get_one::<String>("test").unwrap(), "coffee");

pub fn visible_short_alias(self, name: impl IntoResettable<char>) -> Self

Add an alias, which functions as a visible short flag.

Like Arg::short_alias, except that they are visible inside the help message.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                .long("test")
                .visible_short_alias('t')
                .action(ArgAction::Set))
       .get_matches_from(vec![
            "prog", "-t", "coffee"
        ]);
assert_eq!(m.get_one::<String>("test").unwrap(), "coffee");

pub fn visible_aliases(
    self,
    names: impl IntoIterator<Item = impl Into<Str>>
) -> Self

Add aliases, which function as visible long flags.

Like Arg::aliases, except that they are visible inside the help message.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                .long("test")
                .action(ArgAction::SetTrue)
                .visible_aliases(["something", "awesome", "cool"]))
       .get_matches_from(vec![
            "prog", "--awesome"
        ]);
assert_eq!(*m.get_one::<bool>("test").expect("defaulted by clap"), true);

pub fn visible_short_aliases(self, names: impl IntoIterator<Item = char>) -> Self

Add aliases, which function as visible short flags.

Like Arg::short_aliases, except that they are visible inside the help message.

Examples

let m = Command::new("prog")
            .arg(Arg::new("test")
                .long("test")
                .action(ArgAction::SetTrue)
                .visible_short_aliases(['t', 'e']))
       .get_matches_from(vec![
            "prog", "-t"
        ]);
assert_eq!(*m.get_one::<bool>("test").expect("defaulted by clap"), true);

pub fn index(self, idx: impl IntoResettable<usize>) -> Self

Specifies the index of a positional argument starting at 1.

NOTE: The index refers to position according to other positional argument. It does not define position in the argument list as a whole.

NOTE: You can optionally leave off the index method, and the index will be assigned in order of evaluation. Utilizing the index method allows for setting indexes out of order

NOTE: This is only meant to be used for positional arguments and shouldn’t to be used with Arg::short or Arg::long.

NOTE: When utilized with [Arg::num_args(1..)], only the last positional argument may be defined as having a variable number of arguments (i.e. with the highest index)

Panics

Command will panic! if indexes are skipped (such as defining index(1) and index(3) but not index(2), or a positional argument is defined as multiple and is not the highest index

Examples

Arg::new("config")
    .index(1)

let m = Command::new("prog")
    .arg(Arg::new("mode")
        .index(1))
    .arg(Arg::new("debug")
        .long("debug")
        .action(ArgAction::SetTrue))
    .get_matches_from(vec![
        "prog", "--debug", "fast"
    ]);

assert!(m.contains_id("mode"));
assert_eq!(m.get_one::<String>("mode").unwrap(), "fast"); // notice index(1) means "first positional"
                                                          // *not* first argument

pub fn trailing_var_arg(self, yes: bool) -> Self

This is a “VarArg” and everything that follows should be captured by it, as if the user had used a --.

NOTE: To start the trailing “VarArg” on unknown flags (and not just a positional value), set allow_hyphen_values. Either way, users still have the option to explicitly escape ambiguous arguments with --.

NOTE: Arg::value_delimiter still applies if set.

NOTE: Setting this requires Arg::num_args(..).

Examples

let m = Command::new("myprog")
    .arg(arg!(<cmd> ... "commands to run").trailing_var_arg(true))
    .get_matches_from(vec!["myprog", "arg1", "-r", "val1"]);

let trail: Vec<_> = m.get_many::<String>("cmd").unwrap().collect();
assert_eq!(trail, ["arg1", "-r", "val1"]);

pub fn last(self, yes: bool) -> Self

This arg is the last, or final, positional argument (i.e. has the highest index) and is only able to be accessed via the -- syntax (i.e. $ prog args -- last_arg).

Even, if no other arguments are left to parse, if the user omits the -- syntax they will receive an UnknownArgument error. Setting an argument to .last(true) also allows one to access this arg early using the -- syntax. Accessing an arg early, even with the -- syntax is otherwise not possible.

NOTE: This will change the usage string to look like $ prog [OPTIONS] [-- <ARG>] if ARG is marked as .last(true).

NOTE: This setting will imply crate::Command::dont_collapse_args_in_usage because failing to set this can make the usage string very confusing.

NOTE: This setting only applies to positional arguments, and has no effect on OPTIONS

NOTE: Setting this requires taking values

CAUTION: Using this setting and having child subcommands is not recommended with the exception of also using crate::Command::args_conflicts_with_subcommands (or crate::Command::subcommand_negates_reqs if the argument marked Last is also marked Arg::required)

Examples

Arg::new("args")
    .action(ArgAction::Set)
    .last(true)

Setting last ensures the arg has the highest index of all positional args and requires that the -- syntax be used to access it early.

let res = Command::new("prog")
    .arg(Arg::new("first"))
    .arg(Arg::new("second"))
    .arg(Arg::new("third")
        .action(ArgAction::Set)
        .last(true))
    .try_get_matches_from(vec![
        "prog", "one", "--", "three"
    ]);

assert!(res.is_ok());
let m = res.unwrap();
assert_eq!(m.get_one::<String>("third").unwrap(), "three");
assert_eq!(m.get_one::<String>("second"), None);

Even if the positional argument marked Last is the only argument left to parse, failing to use the -- syntax results in an error.

let res = Command::new("prog")
    .arg(Arg::new("first"))
    .arg(Arg::new("second"))
    .arg(Arg::new("third")
        .action(ArgAction::Set)
        .last(true))
    .try_get_matches_from(vec![
        "prog", "one", "two", "three"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::UnknownArgument);

Examples found in repository

src/builder/arg.rs (line 1587)

    pub fn raw(mut self, yes: bool) -> Self {
        if yes {
            self.num_vals.get_or_insert_with(|| (1..).into());
        }
        self.allow_hyphen_values(yes).last(yes)
    }

pub fn required(self, yes: bool) -> Self

Specifies that the argument must be present.

Required by default means it is required, when no other conflicting rules or overrides have been evaluated. Conflicting rules take precedence over being required.

Pro tip: Flags (i.e. not positional, or arguments that take values) shouldn’t be required by default. This is because if a flag were to be required, it should simply be implied. No additional information is required from user. Flags by their very nature are simply boolean on/off switches. The only time a user should be required to use a flag is if the operation is destructive in nature, and the user is essentially proving to you, “Yes, I know what I’m doing.”

Examples

Arg::new("config")
    .required(true)

Setting required requires that the argument be used at runtime.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required(true)
        .action(ArgAction::Set)
        .long("config"))
    .try_get_matches_from(vec![
        "prog", "--config", "file.conf",
    ]);

assert!(res.is_ok());

Setting required and then not supplying that argument at runtime is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required(true)
        .action(ArgAction::Set)
        .long("config"))
    .try_get_matches_from(vec![
        "prog"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn requires(self, arg_id: impl IntoResettable<Id>) -> Self

Sets an argument that is required when this one is present

i.e. when using this argument, the following argument must be present.

NOTE: Conflicting rules and override rules take precedence over being required

Examples

Arg::new("config")
    .requires("input")

Setting Arg::requires(name) requires that the argument be used at runtime if the defining argument is used. If the defining argument isn’t used, the other argument isn’t required

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires("input")
        .long("config"))
    .arg(Arg::new("input"))
    .try_get_matches_from(vec![
        "prog"
    ]);

assert!(res.is_ok()); // We didn't use cfg, so input wasn't required

Setting Arg::requires(name) and not supplying that argument is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires("input")
        .long("config"))
    .arg(Arg::new("input"))
    .try_get_matches_from(vec![
        "prog", "--config", "file.conf"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn exclusive(self, yes: bool) -> Self

This argument must be passed alone; it conflicts with all other arguments.

Examples

Arg::new("config")
    .exclusive(true)

Setting an exclusive argument and having any other arguments present at runtime is an error.

let res = Command::new("prog")
    .arg(Arg::new("exclusive")
        .action(ArgAction::Set)
        .exclusive(true)
        .long("exclusive"))
    .arg(Arg::new("debug")
        .long("debug"))
    .arg(Arg::new("input"))
    .try_get_matches_from(vec![
        "prog", "--exclusive", "file.conf", "file.txt"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::ArgumentConflict);

pub fn global(self, yes: bool) -> Self

Specifies that an argument can be matched to all child Subcommands.

NOTE: Global arguments only propagate down, not up (to parent commands), however their values once a user uses them will be propagated back up to parents. In effect, this means one should define all global arguments at the top level, however it doesn’t matter where the user uses the global argument.

Examples

Assume an application with two subcommands, and you’d like to define a --verbose flag that can be called on any of the subcommands and parent, but you don’t want to clutter the source with three duplicate Arg definitions.

let m = Command::new("prog")
    .arg(Arg::new("verb")
        .long("verbose")
        .short('v')
        .action(ArgAction::SetTrue)
        .global(true))
    .subcommand(Command::new("test"))
    .subcommand(Command::new("do-stuff"))
    .get_matches_from(vec![
        "prog", "do-stuff", "--verbose"
    ]);

assert_eq!(m.subcommand_name(), Some("do-stuff"));
let sub_m = m.subcommand_matches("do-stuff").unwrap();
assert_eq!(*sub_m.get_one::<bool>("verb").expect("defaulted by clap"), true);

impl Arg

Value Handling

pub fn action(self, action: impl IntoResettable<ArgAction>) -> Self

Specify how to react to an argument when parsing it.

ArgAction controls things like

• Overwriting previous values with new ones
• Appending new values to all previous ones
• Counting how many times a flag occurs

The default action is ArgAction::Set

Examples

let cmd = Command::new("mycmd")
    .arg(
        Arg::new("flag")
            .long("flag")
            .action(clap::ArgAction::Append)
    );

let matches = cmd.try_get_matches_from(["mycmd", "--flag", "value"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(
    matches.get_many::<String>("flag").unwrap_or_default().map(|v| v.as_str()).collect::<Vec<_>>(),
    vec!["value"]
);

Examples found in repository

src/builder/command.rs (line 4243)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn value_parser(self, parser: impl IntoResettable<ValueParser>) -> Self

Specify the typed behavior of the argument.

This allows parsing and validating a value before storing it into ArgMatches as the given type.

Possible value parsers include:

• value_parser!(T) for auto-selecting a value parser for a given type
  • Or range expressions like 0..=1 as a shorthand for RangedI64ValueParser
• Fn(&str) -> Result<T, E>
• [&str] and PossibleValuesParser for static enumerated values
• BoolishValueParser, and FalseyValueParser for alternative bool implementations
• NonEmptyStringValueParser for basic validation for strings
• or any other TypedValueParser implementation

The default value is ValueParser::string.

let mut cmd = clap::Command::new("raw")
    .arg(
        clap::Arg::new("color")
            .long("color")
            .value_parser(["always", "auto", "never"])
            .default_value("auto")
    )
    .arg(
        clap::Arg::new("hostname")
            .long("hostname")
            .value_parser(clap::builder::NonEmptyStringValueParser::new())
            .action(ArgAction::Set)
            .required(true)
    )
    .arg(
        clap::Arg::new("port")
            .long("port")
            .value_parser(clap::value_parser!(u16).range(3000..))
            .action(ArgAction::Set)
            .required(true)
    );

let m = cmd.try_get_matches_from_mut(
    ["cmd", "--hostname", "rust-lang.org", "--port", "3001"]
).unwrap();

let color: &String = m.get_one("color")
    .expect("default");
assert_eq!(color, "auto");

let hostname: &String = m.get_one("hostname")
    .expect("required");
assert_eq!(hostname, "rust-lang.org");

let port: u16 = *m.get_one("port")
    .expect("required");
assert_eq!(port, 3001);

pub fn num_args(self, qty: impl IntoResettable<ValueRange>) -> Self

Specifies the number of arguments parsed per occurrence

For example, if you had a -f <file> argument where you wanted exactly 3 ‘files’ you would set .num_args(3), and this argument wouldn’t be satisfied unless the user provided 3 and only 3 values.

Users may specify values for arguments in any of the following methods

• Using a space such as -o value or --option value
• Using an equals and no space such as -o=value or --option=value
• Use a short and no space such as -ovalue

WARNING:

Setting a variable number of values (e.g. 1..=10) for an argument without other details can be dangerous in some circumstances. Because multiple values are allowed, --option val1 val2 val3 is perfectly valid. Be careful when designing a CLI where positional arguments or subcommands are also expected as clap will continue parsing values until one of the following happens:

• It reaches the maximum number of values
• It reaches a specific number of values
• It finds another flag or option (i.e. something that starts with a -)
• It reaches the Arg::value_terminator if set

Alternatively,

• Use a delimiter between values with Arg::value_delimiter
• Require a flag occurrence per value with ArgAction::Append
• Require positional arguments to appear after -- with Arg::last

Examples

Option:

let m = Command::new("prog")
    .arg(Arg::new("mode")
        .long("mode")
        .num_args(1))
    .get_matches_from(vec![
        "prog", "--mode", "fast"
    ]);

assert_eq!(m.get_one::<String>("mode").unwrap(), "fast");

Flag/option hybrid (see also default_missing_value)

let cmd = Command::new("prog")
    .arg(Arg::new("mode")
        .long("mode")
        .default_missing_value("slow")
        .default_value("plaid")
        .num_args(0..=1));

let m = cmd.clone()
    .get_matches_from(vec![
        "prog", "--mode", "fast"
    ]);
assert_eq!(m.get_one::<String>("mode").unwrap(), "fast");

let m = cmd.clone()
    .get_matches_from(vec![
        "prog", "--mode",
    ]);
assert_eq!(m.get_one::<String>("mode").unwrap(), "slow");

let m = cmd.clone()
    .get_matches_from(vec![
        "prog",
    ]);
assert_eq!(m.get_one::<String>("mode").unwrap(), "plaid");

Tuples

let cmd = Command::new("prog")
    .arg(Arg::new("file")
        .action(ArgAction::Set)
        .num_args(2)
        .short('F'));

let m = cmd.clone()
    .get_matches_from(vec![
        "prog", "-F", "in-file", "out-file"
    ]);
assert_eq!(
    m.get_many::<String>("file").unwrap_or_default().map(|v| v.as_str()).collect::<Vec<_>>(),
    vec!["in-file", "out-file"]
);

let res = cmd.clone()
    .try_get_matches_from(vec![
        "prog", "-F", "file1"
    ]);
assert_eq!(res.unwrap_err().kind(), ErrorKind::WrongNumberOfValues);

A common mistake is to define an option which allows multiple values and a positional argument.

let cmd = Command::new("prog")
    .arg(Arg::new("file")
        .action(ArgAction::Set)
        .num_args(0..)
        .short('F'))
    .arg(Arg::new("word"));

let m = cmd.clone().get_matches_from(vec![
    "prog", "-F", "file1", "file2", "file3", "word"
]);
let files: Vec<_> = m.get_many::<String>("file").unwrap().collect();
assert_eq!(files, ["file1", "file2", "file3", "word"]); // wait...what?!
assert!(!m.contains_id("word")); // but we clearly used word!

// but this works
let m = cmd.clone().get_matches_from(vec![
    "prog", "word", "-F", "file1", "file2", "file3",
]);
let files: Vec<_> = m.get_many::<String>("file").unwrap().collect();
assert_eq!(files, ["file1", "file2", "file3"]);
assert_eq!(m.get_one::<String>("word").unwrap(), "word");

The problem is clap doesn’t know when to stop parsing values for “file”.

A solution for the example above is to limit how many values with a maximum, or specific number, or to say ArgAction::Append is ok, but multiple values are not.

let m = Command::new("prog")
    .arg(Arg::new("file")
        .action(ArgAction::Append)
        .short('F'))
    .arg(Arg::new("word"))
    .get_matches_from(vec![
        "prog", "-F", "file1", "-F", "file2", "-F", "file3", "word"
    ]);

let files: Vec<_> = m.get_many::<String>("file").unwrap().collect();
assert_eq!(files, ["file1", "file2", "file3"]);
assert_eq!(m.get_one::<String>("word").unwrap(), "word");

Examples found in repository

src/builder/arg.rs (line 1106)

    pub fn number_of_values(self, qty: usize) -> Self {
        self.num_args(qty)
    }

src/builder/command.rs (line 4290)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn value_name(self, name: impl IntoResettable<Str>) -> Self

Placeholder for the argument’s value in the help message / usage.

This name is cosmetic only; the name is not used to access arguments. This setting can be very helpful when describing the type of input the user should be using, such as FILE, INTERFACE, etc. Although not required, it’s somewhat convention to use all capital letters for the value name.

NOTE: implicitly sets Arg::action(ArgAction::Set)

Examples

Arg::new("cfg")
    .long("config")
    .value_name("FILE")

let m = Command::new("prog")
   .arg(Arg::new("config")
       .long("config")
       .value_name("FILE")
       .help("Some help text"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

Running the above program produces the following output

valnames

Usage: valnames [OPTIONS]

Options:
    --config <FILE>     Some help text
    -h, --help          Print help information
    -V, --version       Print version information

Examples found in repository

src/builder/command.rs (line 4291)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn value_names(self, names: impl IntoIterator<Item = impl Into<Str>>) -> Self

Placeholders for the argument’s values in the help message / usage.

These names are cosmetic only, used for help and usage strings only. The names are not used to access arguments. The values of the arguments are accessed in numeric order (i.e. if you specify two names one and two one will be the first matched value, two will be the second).

This setting can be very helpful when describing the type of input the user should be using, such as FILE, INTERFACE, etc. Although not required, it’s somewhat convention to use all capital letters for the value name.

Pro Tip: It may help to use Arg::next_line_help(true) if there are long, or multiple value names in order to not throw off the help text alignment of all options.

NOTE: implicitly sets Arg::action(ArgAction::Set) and Arg::num_args(1..).

Examples

Arg::new("speed")
    .short('s')
    .value_names(["fast", "slow"]);

let m = Command::new("prog")
   .arg(Arg::new("io")
       .long("io-files")
       .value_names(["INFILE", "OUTFILE"]))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

Running the above program produces the following output

valnames

Usage: valnames [OPTIONS]

Options:
    -h, --help                       Print help information
    --io-files <INFILE> <OUTFILE>    Some help text
    -V, --version                    Print version information

Examples found in repository

src/builder/arg.rs (line 1158)

    pub fn value_name(mut self, name: impl IntoResettable<Str>) -> Self {
        if let Some(name) = name.into_resettable().into_option() {
            self.value_names([name])
        } else {
            self.val_names.clear();
            self
        }
    }

pub fn value_hint(self, value_hint: impl IntoResettable<ValueHint>) -> Self

Provide the shell a hint about how to complete this argument.

See ValueHint for more information.

NOTE: implicitly sets [Arg::action(ArgAction::Set)].

For example, to take a username as argument:

Arg::new("user")
    .short('u')
    .long("user")
    .value_hint(ValueHint::Username);

To take a full command line and its arguments (for example, when writing a command wrapper):

Command::new("prog")
    .trailing_var_arg(true)
    .arg(
        Arg::new("command")
            .action(ArgAction::Set)
            .num_args(1..)
            .value_hint(ValueHint::CommandWithArguments)
    );

pub fn ignore_case(self, yes: bool) -> Self

Match values against PossibleValuesParser without matching case.

When other arguments are conditionally required based on the value of a case-insensitive argument, the equality check done by Arg::required_if_eq, Arg::required_if_eq_any, or Arg::required_if_eq_all is case-insensitive.

NOTE: Setting this requires taking values

NOTE: To do unicode case folding, enable the unicode feature flag.

Examples

let m = Command::new("pv")
    .arg(Arg::new("option")
        .long("option")
        .action(ArgAction::Set)
        .ignore_case(true)
        .value_parser(["test123"]))
    .get_matches_from(vec![
        "pv", "--option", "TeSt123",
    ]);

assert!(m.get_one::<String>("option").unwrap().eq_ignore_ascii_case("test123"));

This setting also works when multiple values can be defined:

let m = Command::new("pv")
    .arg(Arg::new("option")
        .short('o')
        .long("option")
        .action(ArgAction::Set)
        .ignore_case(true)
        .num_args(1..)
        .value_parser(["test123", "test321"]))
    .get_matches_from(vec![
        "pv", "--option", "TeSt123", "teST123", "tESt321"
    ]);

let matched_vals = m.get_many::<String>("option").unwrap().collect::<Vec<_>>();
assert_eq!(&*matched_vals, &["TeSt123", "teST123", "tESt321"]);

pub fn allow_hyphen_values(self, yes: bool) -> Self

Allows values which start with a leading hyphen (-)

To limit values to just numbers, see allow_negative_numbers.

See also trailing_var_arg.

NOTE: Setting this requires taking values

WARNING: Prior arguments with allow_hyphen_values(true) get precedence over known flags but known flags get precedence over the next possible positional argument with allow_hyphen_values(true). When combined with [Arg::num_args(..)], Arg::value_terminator is one way to ensure processing stops.

WARNING: Take caution when using this setting combined with another argument using Arg::num_args, as this becomes ambiguous $ prog --arg -- -- val. All three --, --, val will be values when the user may have thought the second -- would constitute the normal, “Only positional args follow” idiom.

Examples

let m = Command::new("prog")
    .arg(Arg::new("pat")
        .action(ArgAction::Set)
        .allow_hyphen_values(true)
        .long("pattern"))
    .get_matches_from(vec![
        "prog", "--pattern", "-file"
    ]);

assert_eq!(m.get_one::<String>("pat").unwrap(), "-file");

Not setting Arg::allow_hyphen_values(true) and supplying a value which starts with a hyphen is an error.

let res = Command::new("prog")
    .arg(Arg::new("pat")
        .action(ArgAction::Set)
        .long("pattern"))
    .try_get_matches_from(vec![
        "prog", "--pattern", "-file"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::UnknownArgument);

Examples found in repository

src/builder/arg.rs (line 1587)

    pub fn raw(mut self, yes: bool) -> Self {
        if yes {
            self.num_vals.get_or_insert_with(|| (1..).into());
        }
        self.allow_hyphen_values(yes).last(yes)
    }

pub fn allow_negative_numbers(self, yes: bool) -> Self

Allows negative numbers to pass as values.

This is similar to Arg::allow_hyphen_values except that it only allows numbers, all other undefined leading hyphens will fail to parse.

NOTE: Setting this requires taking values

Examples

let res = Command::new("myprog")
    .arg(Arg::new("num").allow_negative_numbers(true))
    .try_get_matches_from(vec![
        "myprog", "-20"
    ]);
assert!(res.is_ok());
let m = res.unwrap();
assert_eq!(m.get_one::<String>("num").unwrap(), "-20");

pub fn require_equals(self, yes: bool) -> Self

Requires that options use the --option=val syntax

i.e. an equals between the option and associated value.

NOTE: Setting this requires taking values

Examples

Setting require_equals requires that the option have an equals sign between it and the associated value.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .require_equals(true)
        .long("config"))
    .try_get_matches_from(vec![
        "prog", "--config=file.conf"
    ]);

assert!(res.is_ok());

Setting require_equals and not supplying the equals will cause an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .require_equals(true)
        .long("config"))
    .try_get_matches_from(vec![
        "prog", "--config", "file.conf"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::NoEquals);

pub fn value_delimiter(self, d: impl IntoResettable<char>) -> Self

Allow grouping of multiple values via a delimiter.

i.e. should --option=val1,val2,val3 be parsed as three values (val1, val2, and val3) or as a single value (val1,val2,val3). Defaults to using , (comma) as the value delimiter for all arguments that accept values (options and positional arguments)

NOTE: implicitly sets Arg::action(ArgAction::Set)

Examples

let m = Command::new("prog")
    .arg(Arg::new("config")
        .short('c')
        .long("config")
        .value_delimiter(','))
    .get_matches_from(vec![
        "prog", "--config=val1,val2,val3"
    ]);

assert_eq!(m.get_many::<String>("config").unwrap().collect::<Vec<_>>(), ["val1", "val2", "val3"])

pub fn value_terminator(self, term: impl IntoResettable<Str>) -> Self

Sentinel to stop parsing multiple values of a given argument.

By default when one sets num_args(1..) on an argument, clap will continue parsing values for that argument until it reaches another valid argument, or one of the other more specific settings for multiple values is used (such as num_args).

NOTE: This setting only applies to options and positional arguments

NOTE: When the terminator is passed in on the command line, it is not stored as one of the values

Examples

Arg::new("vals")
    .action(ArgAction::Set)
    .num_args(1..)
    .value_terminator(";")

The following example uses two arguments, a sequence of commands, and the location in which to perform them

let m = Command::new("prog")
    .arg(Arg::new("cmds")
        .action(ArgAction::Set)
        .num_args(1..)
        .allow_hyphen_values(true)
        .value_terminator(";"))
    .arg(Arg::new("location"))
    .get_matches_from(vec![
        "prog", "find", "-type", "f", "-name", "special", ";", "/home/clap"
    ]);
let cmds: Vec<_> = m.get_many::<String>("cmds").unwrap().collect();
assert_eq!(&cmds, &["find", "-type", "f", "-name", "special"]);
assert_eq!(m.get_one::<String>("location").unwrap(), "/home/clap");

pub fn raw(self, yes: bool) -> Self

Consume all following arguments.

Do not be parse them individually, but rather pass them in entirety.

It is worth noting that setting this requires all values to come after a -- to indicate they should all be captured. For example:

--foo something -- -v -v -v -b -b -b --baz -q -u -x

Will result in everything after -- to be considered one raw argument. This behavior may not be exactly what you are expecting and using crate::Command::trailing_var_arg may be more appropriate.

NOTE: Implicitly sets Arg::action(ArgAction::Set) Arg::num_args(1..), Arg::allow_hyphen_values(true), and Arg::last(true) when set to true.

pub fn default_value(self, val: impl IntoResettable<OsStr>) -> Self

Value for the argument when not present.

NOTE: If the user does not use this argument at runtime ArgMatches::contains_id will still return true. If you wish to determine whether the argument was used at runtime or not, consider ArgMatches::value_source.

NOTE: This setting is perfectly compatible with Arg::default_value_if but slightly different. Arg::default_value only takes effect when the user has not provided this arg at runtime. Arg::default_value_if however only takes effect when the user has not provided a value at runtime and these other conditions are met as well. If you have set Arg::default_value and Arg::default_value_if, and the user did not provide this arg at runtime, nor were the conditions met for Arg::default_value_if, the Arg::default_value will be applied.

NOTE: This implicitly sets Arg::action(ArgAction::Set).

Examples

First we use the default value without providing any value at runtime.

let m = Command::new("prog")
    .arg(Arg::new("opt")
        .long("myopt")
        .default_value("myval"))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_one::<String>("opt").unwrap(), "myval");
assert!(m.contains_id("opt"));
assert_eq!(m.value_source("opt"), Some(ValueSource::DefaultValue));

Next we provide a value at runtime to override the default.

let m = Command::new("prog")
    .arg(Arg::new("opt")
        .long("myopt")
        .default_value("myval"))
    .get_matches_from(vec![
        "prog", "--myopt=non_default"
    ]);

assert_eq!(m.get_one::<String>("opt").unwrap(), "non_default");
assert!(m.contains_id("opt"));
assert_eq!(m.value_source("opt"), Some(ValueSource::CommandLine));

pub fn default_values(
    self,
    vals: impl IntoIterator<Item = impl Into<OsStr>>
) -> Self

Value for the argument when not present.

See Arg::default_value.

Examples found in repository

src/builder/arg.rs (line 1648)

    pub fn default_value(mut self, val: impl IntoResettable<OsStr>) -> Self {
        if let Some(val) = val.into_resettable().into_option() {
            self.default_values([val])
        } else {
            self.default_vals.clear();
            self
        }
    }

    #[inline]
    #[must_use]
    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(since = "4.0.0", note = "Replaced with `Arg::default_value`")
    )]
    pub fn default_value_os(self, val: impl Into<OsStr>) -> Self {
        self.default_values([val])
    }

    /// Value for the argument when not present.
    ///
    /// See [`Arg::default_value`].
    ///
    /// [`Arg::default_value`]: Arg::default_value()
    #[inline]
    #[must_use]
    pub fn default_values(mut self, vals: impl IntoIterator<Item = impl Into<OsStr>>) -> Self {
        self.default_vals = vals.into_iter().map(|s| s.into()).collect();
        self
    }

    #[inline]
    #[must_use]
    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(since = "4.0.0", note = "Replaced with `Arg::default_values`")
    )]
    pub fn default_values_os(self, vals: impl IntoIterator<Item = impl Into<OsStr>>) -> Self {
        self.default_values(vals)
    }

pub fn default_missing_value(self, val: impl IntoResettable<OsStr>) -> Self

Value for the argument when the flag is present but no value is specified.

This configuration option is often used to give the user a shortcut and allow them to efficiently specify an option argument without requiring an explicitly value. The --color argument is a common example. By, supplying an default, such as default_missing_value("always"), the user can quickly just add --color to the command line to produce the desired color output.

NOTE: using this configuration option requires the use of the .num_args(0..N) and the .require_equals(true) configuration option. These are required in order to unambiguously determine what, if any, value was supplied for the argument.

Examples

For POSIX style --color:

fn cli() -> Command {
    Command::new("prog")
        .arg(Arg::new("color").long("color")
            .value_name("WHEN")
            .value_parser(["always", "auto", "never"])
            .default_value("auto")
            .num_args(0..=1)
            .require_equals(true)
            .default_missing_value("always")
            .help("Specify WHEN to colorize output.")
        )
}

// first, we'll provide no arguments
let m  = cli().get_matches_from(vec![
        "prog"
    ]);
assert_eq!(m.get_one::<String>("color").unwrap(), "auto");
assert_eq!(m.value_source("color"), Some(ValueSource::DefaultValue));

// next, we'll provide a runtime value to override the default (as usually done).
let m  = cli().get_matches_from(vec![
        "prog", "--color=never"
    ]);
assert_eq!(m.get_one::<String>("color").unwrap(), "never");
assert_eq!(m.value_source("color"), Some(ValueSource::CommandLine));

// finally, we will use the shortcut and only provide the argument without a value.
let m  = cli().get_matches_from(vec![
        "prog", "--color"
    ]);
assert_eq!(m.get_one::<String>("color").unwrap(), "always");
assert_eq!(m.value_source("color"), Some(ValueSource::CommandLine));

For bool literals:

fn cli() -> Command {
    Command::new("prog")
        .arg(Arg::new("create").long("create")
            .value_name("BOOL")
            .value_parser(value_parser!(bool))
            .num_args(0..=1)
            .require_equals(true)
            .default_missing_value("true")
        )
}

// first, we'll provide no arguments
let m  = cli().get_matches_from(vec![
        "prog"
    ]);
assert_eq!(m.get_one::<bool>("create").copied(), None);

// next, we'll provide a runtime value to override the default (as usually done).
let m  = cli().get_matches_from(vec![
        "prog", "--create=false"
    ]);
assert_eq!(m.get_one::<bool>("create").copied(), Some(false));
assert_eq!(m.value_source("create"), Some(ValueSource::CommandLine));

// finally, we will use the shortcut and only provide the argument without a value.
let m  = cli().get_matches_from(vec![
        "prog", "--create"
    ]);
assert_eq!(m.get_one::<bool>("create").copied(), Some(true));
assert_eq!(m.value_source("create"), Some(ValueSource::CommandLine));

pub fn default_missing_value_os(self, val: impl Into<OsStr>) -> Self

Value for the argument when the flag is present but no value is specified.

See Arg::default_missing_value.

pub fn default_missing_values(
    self,
    vals: impl IntoIterator<Item = impl Into<OsStr>>
) -> Self

Value for the argument when the flag is present but no value is specified.

See Arg::default_missing_value.

pub fn default_missing_values_os(
    self,
    vals: impl IntoIterator<Item = impl Into<OsStr>>
) -> Self

Value for the argument when the flag is present but no value is specified.

See Arg::default_missing_values.

Examples found in repository

src/builder/arg.rs (line 1782)

    pub fn default_missing_value(mut self, val: impl IntoResettable<OsStr>) -> Self {
        if let Some(val) = val.into_resettable().into_option() {
            self.default_missing_values_os([val])
        } else {
            self.default_missing_vals.clear();
            self
        }
    }

    /// Value for the argument when the flag is present but no value is specified.
    ///
    /// See [`Arg::default_missing_value`].
    ///
    /// [`Arg::default_missing_value`]: Arg::default_missing_value()
    /// [`OsStr`]: std::ffi::OsStr
    #[inline]
    #[must_use]
    pub fn default_missing_value_os(self, val: impl Into<OsStr>) -> Self {
        self.default_missing_values_os([val])
    }

    /// Value for the argument when the flag is present but no value is specified.
    ///
    /// See [`Arg::default_missing_value`].
    ///
    /// [`Arg::default_missing_value`]: Arg::default_missing_value()
    #[inline]
    #[must_use]
    pub fn default_missing_values(self, vals: impl IntoIterator<Item = impl Into<OsStr>>) -> Self {
        self.default_missing_values_os(vals)
    }

pub fn env(self, name: impl IntoResettable<OsStr>) -> Self

Available on crate feature env only.

Read from name environment variable when argument is not present.

If it is not present in the environment, then default rules will apply.

If user sets the argument in the environment:

• When Arg::action(ArgAction::Set) is not set, the flag is considered raised.
• When Arg::action(ArgAction::Set) is set, ArgMatches::get_one will return value of the environment variable.

If user doesn’t set the argument in the environment:

• When Arg::action(ArgAction::Set) is not set, the flag is considered off.
• When Arg::action(ArgAction::Set) is set, ArgMatches::get_one will return the default specified.

Examples

In this example, we show the variable coming from the environment:

env::set_var("MY_FLAG", "env");

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .env("MY_FLAG")
        .action(ArgAction::Set))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_one::<String>("flag").unwrap(), "env");

In this example, because prog is a flag that accepts an optional, case-insensitive boolean literal.

Note that the value parser controls how flags are parsed. In this case we’ve selected FalseyValueParser. A false literal is n, no, f, false, off or 0. An absent environment variable will also be considered as false. Anything else will considered as true.

env::set_var("TRUE_FLAG", "true");
env::set_var("FALSE_FLAG", "0");

let m = Command::new("prog")
    .arg(Arg::new("true_flag")
        .long("true_flag")
        .action(ArgAction::SetTrue)
        .value_parser(FalseyValueParser::new())
        .env("TRUE_FLAG"))
    .arg(Arg::new("false_flag")
        .long("false_flag")
        .action(ArgAction::SetTrue)
        .value_parser(FalseyValueParser::new())
        .env("FALSE_FLAG"))
    .arg(Arg::new("absent_flag")
        .long("absent_flag")
        .action(ArgAction::SetTrue)
        .value_parser(FalseyValueParser::new())
        .env("ABSENT_FLAG"))
    .get_matches_from(vec![
        "prog"
    ]);

assert!(*m.get_one::<bool>("true_flag").unwrap());
assert!(!*m.get_one::<bool>("false_flag").unwrap());
assert!(!*m.get_one::<bool>("absent_flag").unwrap());

In this example, we show the variable coming from an option on the CLI:

env::set_var("MY_FLAG", "env");

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .env("MY_FLAG")
        .action(ArgAction::Set))
    .get_matches_from(vec![
        "prog", "--flag", "opt"
    ]);

assert_eq!(m.get_one::<String>("flag").unwrap(), "opt");

In this example, we show the variable coming from the environment even with the presence of a default:

env::set_var("MY_FLAG", "env");

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .env("MY_FLAG")
        .action(ArgAction::Set)
        .default_value("default"))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_one::<String>("flag").unwrap(), "env");

In this example, we show the use of multiple values in a single environment variable:

env::set_var("MY_FLAG_MULTI", "env1,env2");

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .env("MY_FLAG_MULTI")
        .action(ArgAction::Set)
        .num_args(1..)
        .value_delimiter(','))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_many::<String>("flag").unwrap().collect::<Vec<_>>(), vec!["env1", "env2"]);

Examples found in repository

src/builder/arg.rs (line 1993)

    pub fn env_os(self, name: impl Into<OsStr>) -> Self {
        self.env(name)
    }

impl Arg

Help

pub fn help(self, h: impl IntoResettable<StyledStr>) -> Self

Sets the description of the argument for short help (-h).

Typically, this is a short (one line) description of the arg.

If Arg::long_help is not specified, this message will be displayed for --help.

NOTE: Only Arg::help is used in completion script generation in order to be concise

Examples

Any valid UTF-8 is allowed in the help text. The one exception is when one wishes to include a newline in the help text and have the following text be properly aligned with all the other help text.

Setting help displays a short message to the side of the argument when the user passes -h or --help (by default).

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays

helptest

Usage: helptest [OPTIONS]

Options:
    --config     Some help text describing the --config arg
-h, --help       Print help information
-V, --version    Print version information

Examples found in repository

src/builder/command.rs (line 4246)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn long_help(self, h: impl IntoResettable<StyledStr>) -> Self

Sets the description of the argument for long help (--help).

Typically this a more detailed (multi-line) message that describes the arg.

If Arg::help is not specified, this message will be displayed for -h.

NOTE: Only Arg::help is used in completion script generation in order to be concise

Examples

Any valid UTF-8 is allowed in the help text. The one exception is when one wishes to include a newline in the help text and have the following text be properly aligned with all the other help text.

Setting help displays a short message to the side of the argument when the user passes -h or --help (by default).

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .long_help(
"The config file used by the myprog must be in JSON format
with only valid keys and may not contain other nonsense
that cannot be read by this program. Obviously I'm going on
and on, so I'll stop now."))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays

prog

Usage: prog [OPTIONS]

Options:
        --config
            The config file used by the myprog must be in JSON format
            with only valid keys and may not contain other nonsense
            that cannot be read by this program. Obviously I'm going on
            and on, so I'll stop now.

    -h, --help
            Print help information

    -V, --version
            Print version information

Examples found in repository

src/builder/command.rs (line 4247)

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

pub fn display_order(self, ord: impl IntoResettable<usize>) -> Self

Allows custom ordering of args within the help message.

Args with a lower value will be displayed first in the help message. This is helpful when one would like to emphasise frequently used args, or prioritize those towards the top of the list. Args with duplicate display orders will be displayed in alphabetical order.

NOTE: The default is 999 for all arguments.

NOTE: This setting is ignored for positional arguments which are always displayed in index order.

Examples

let m = Command::new("prog")
   .arg(Arg::new("a") // Typically args are grouped alphabetically by name.
                            // Args without a display_order have a value of 999 and are
                            // displayed alphabetically with all other 999 valued args.
       .long("long-option")
       .short('o')
       .action(ArgAction::Set)
       .help("Some help and text"))
   .arg(Arg::new("b")
       .long("other-option")
       .short('O')
       .action(ArgAction::Set)
       .display_order(1)   // In order to force this arg to appear *first*
                           // all we have to do is give it a value lower than 999.
                           // Any other args with a value of 1 will be displayed
                           // alphabetically with this one...then 2 values, then 3, etc.
       .help("I should be first!"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays the following help message

cust-ord

Usage: cust-ord [OPTIONS]

Options:
    -h, --help                Print help information
    -V, --version             Print version information
    -O, --other-option <b>    I should be first!
    -o, --long-option <a>     Some help and text

pub fn help_heading(self, heading: impl IntoResettable<Str>) -> Self

Override the current help section.

pub fn next_line_help(self, yes: bool) -> Self

Render the help on the line after the argument.

This can be helpful for arguments with very long or complex help messages. This can also be helpful for arguments with very long flag names, or many/long value names.

NOTE: To apply this setting to all arguments and subcommands, consider using crate::Command::next_line_help

Examples

let m = Command::new("prog")
   .arg(Arg::new("opt")
       .long("long-option-flag")
       .short('o')
       .action(ArgAction::Set)
       .next_line_help(true)
       .value_names(["value1", "value2"])
       .help("Some really long help and complex\n\
              help that makes more sense to be\n\
              on a line after the option"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays the following help message

nlh

Usage: nlh [OPTIONS]

Options:
    -h, --help       Print help information
    -V, --version    Print version information
    -o, --long-option-flag <value1> <value2>
        Some really long help and complex
        help that makes more sense to be
        on a line after the option

pub fn hide(self, yes: bool) -> Self

Do not display the argument in help message.

NOTE: This does not hide the argument from usage strings on error

Examples

Setting Hidden will hide the argument when displaying help text

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .hide(true)
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays

helptest

Usage: helptest [OPTIONS]

Options:
-h, --help       Print help information
-V, --version    Print version information

pub fn hide_possible_values(self, yes: bool) -> Self

Do not display the possible values in the help message.

This is useful for args with many values, or ones which are explained elsewhere in the help text.

NOTE: Setting this requires taking values

To set this for all arguments, see Command::hide_possible_values.

Examples

let m = Command::new("prog")
    .arg(Arg::new("mode")
        .long("mode")
        .value_parser(["fast", "slow"])
        .action(ArgAction::Set)
        .hide_possible_values(true));

If we were to run the above program with --help the [values: fast, slow] portion of the help text would be omitted.

pub fn hide_default_value(self, yes: bool) -> Self

Do not display the default value of the argument in the help message.

This is useful when default behavior of an arg is explained elsewhere in the help text.

NOTE: Setting this requires taking values

Examples

let m = Command::new("connect")
    .arg(Arg::new("host")
        .long("host")
        .default_value("localhost")
        .action(ArgAction::Set)
        .hide_default_value(true));

If we were to run the above program with --help the [default: localhost] portion of the help text would be omitted.

pub fn hide_env(self, yes: bool) -> Self

Available on crate feature env only.

Do not display in help the environment variable name.

This is useful when the variable option is explained elsewhere in the help text.

Examples

let m = Command::new("prog")
    .arg(Arg::new("mode")
        .long("mode")
        .env("MODE")
        .action(ArgAction::Set)
        .hide_env(true));

If we were to run the above program with --help the [env: MODE] portion of the help text would be omitted.

pub fn hide_env_values(self, yes: bool) -> Self

Available on crate feature env only.

Do not display in help any values inside the associated ENV variables for the argument.

This is useful when ENV vars contain sensitive values.

Examples

let m = Command::new("connect")
    .arg(Arg::new("host")
        .long("host")
        .env("CONNECT")
        .action(ArgAction::Set)
        .hide_env_values(true));

If we were to run the above program with $ CONNECT=super_secret connect --help the [default: CONNECT=super_secret] portion of the help text would be omitted.

pub fn hide_short_help(self, yes: bool) -> Self

Hides an argument from short help (-h).

NOTE: This does not hide the argument from usage strings on error

NOTE: Setting this option will cause next-line-help output style to be used when long help (--help) is called.

Examples

Arg::new("debug")
    .hide_short_help(true);

Setting hide_short_help(true) will hide the argument when displaying short help text

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .hide_short_help(true)
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "-h"
   ]);

The above example displays

helptest

Usage: helptest [OPTIONS]

Options:
-h, --help       Print help information
-V, --version    Print version information

However, when –help is called

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .hide_short_help(true)
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

Then the following would be displayed

helptest

Usage: helptest [OPTIONS]

Options:
    --config     Some help text describing the --config arg
-h, --help       Print help information
-V, --version    Print version information

pub fn hide_long_help(self, yes: bool) -> Self

Hides an argument from long help (--help).

NOTE: This does not hide the argument from usage strings on error

NOTE: Setting this option will cause next-line-help output style to be used when long help (--help) is called.

Examples

Setting hide_long_help(true) will hide the argument when displaying long help text

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .hide_long_help(true)
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "--help"
   ]);

The above example displays

helptest

Usage: helptest [OPTIONS]

Options:
-h, --help       Print help information
-V, --version    Print version information

However, when -h is called

let m = Command::new("prog")
   .arg(Arg::new("cfg")
       .long("config")
       .hide_long_help(true)
       .help("Some help text describing the --config arg"))
   .get_matches_from(vec![
       "prog", "-h"
   ]);

Then the following would be displayed

helptest

Usage: helptest [OPTIONS]

OPTIONS:
    --config     Some help text describing the --config arg
-h, --help       Print help information
-V, --version    Print version information

impl Arg

Advanced Argument Relations

pub fn group(self, group_id: impl IntoResettable<Id>) -> Self

The name of the ArgGroup the argument belongs to.

Examples

Arg::new("debug")
    .long("debug")
    .action(ArgAction::SetTrue)
    .group("mode")

Multiple arguments can be a member of a single group and then the group checked as if it was one of said arguments.

let m = Command::new("prog")
    .arg(Arg::new("debug")
        .long("debug")
        .action(ArgAction::SetTrue)
        .group("mode"))
    .arg(Arg::new("verbose")
        .long("verbose")
        .action(ArgAction::SetTrue)
        .group("mode"))
    .get_matches_from(vec![
        "prog", "--debug"
    ]);
assert!(m.contains_id("mode"));

pub fn groups(self, group_ids: impl IntoIterator<Item = impl Into<Id>>) -> Self

The names of ArgGroup’s the argument belongs to.

Examples

Arg::new("debug")
    .long("debug")
    .action(ArgAction::SetTrue)
    .groups(["mode", "verbosity"])

Arguments can be members of multiple groups and then the group checked as if it was one of said arguments.

let m = Command::new("prog")
    .arg(Arg::new("debug")
        .long("debug")
        .action(ArgAction::SetTrue)
        .groups(["mode", "verbosity"]))
    .arg(Arg::new("verbose")
        .long("verbose")
        .action(ArgAction::SetTrue)
        .groups(["mode", "verbosity"]))
    .get_matches_from(vec![
        "prog", "--debug"
    ]);
assert!(m.contains_id("mode"));
assert!(m.contains_id("verbosity"));

pub fn default_value_if(
    self,
    arg_id: impl Into<Id>,
    predicate: impl Into<ArgPredicate>,
    default: impl IntoResettable<OsStr>
) -> Self

Specifies the value of the argument if arg has been used at runtime.

If default is set to None, default_value will be removed.

NOTE: This setting is perfectly compatible with Arg::default_value but slightly different. Arg::default_value only takes effect when the user has not provided this arg at runtime. This setting however only takes effect when the user has not provided a value at runtime and these other conditions are met as well. If you have set Arg::default_value and Arg::default_value_if, and the user did not provide this arg at runtime, nor were the conditions met for Arg::default_value_if, the Arg::default_value will be applied.

NOTE: This implicitly sets Arg::action(ArgAction::Set).

Examples

First we use the default value only if another arg is present at runtime.

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("other")
        .long("other")
        .default_value_if("flag", ArgPredicate::IsPresent, Some("default")))
    .get_matches_from(vec![
        "prog", "--flag"
    ]);

assert_eq!(m.get_one::<String>("other").unwrap(), "default");

Next we run the same test, but without providing --flag.

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("other")
        .long("other")
        .default_value_if("flag", "true", Some("default")))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_one::<String>("other"), None);

Now lets only use the default value if --opt contains the value special.

let m = Command::new("prog")
    .arg(Arg::new("opt")
        .action(ArgAction::Set)
        .long("opt"))
    .arg(Arg::new("other")
        .long("other")
        .default_value_if("opt", "special", Some("default")))
    .get_matches_from(vec![
        "prog", "--opt", "special"
    ]);

assert_eq!(m.get_one::<String>("other").unwrap(), "default");

We can run the same test and provide any value other than special and we won’t get a default value.

let m = Command::new("prog")
    .arg(Arg::new("opt")
        .action(ArgAction::Set)
        .long("opt"))
    .arg(Arg::new("other")
        .long("other")
        .default_value_if("opt", "special", Some("default")))
    .get_matches_from(vec![
        "prog", "--opt", "hahaha"
    ]);

assert_eq!(m.get_one::<String>("other"), None);

If we want to unset the default value for an Arg based on the presence or value of some other Arg.

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("other")
        .long("other")
        .default_value("default")
        .default_value_if("flag", "true", None))
    .get_matches_from(vec![
        "prog", "--flag"
    ]);

assert_eq!(m.get_one::<String>("other"), None);

Examples found in repository

src/builder/arg.rs (line 2775)

    pub fn default_value_if_os(
        self,
        arg_id: impl Into<Id>,
        predicate: impl Into<ArgPredicate>,
        default: impl IntoResettable<OsStr>,
    ) -> Self {
        self.default_value_if(arg_id, predicate, default)
    }

    /// Specifies multiple values and conditions in the same manner as [`Arg::default_value_if`].
    ///
    /// The method takes a slice of tuples in the `(arg, predicate, default)` format.
    ///
    /// **NOTE**: The conditions are stored in order and evaluated in the same order. I.e. the first
    /// if multiple conditions are true, the first one found will be applied and the ultimate value.
    ///
    /// # Examples
    ///
    /// First we use the default value only if another arg is present at runtime.
    ///
    /// ```rust
    /// # use clap::{Command, Arg, ArgAction};
    /// let m = Command::new("prog")
    ///     .arg(Arg::new("flag")
    ///         .long("flag")
    ///         .action(ArgAction::SetTrue))
    ///     .arg(Arg::new("opt")
    ///         .long("opt")
    ///         .action(ArgAction::Set))
    ///     .arg(Arg::new("other")
    ///         .long("other")
    ///         .default_value_ifs([
    ///             ("flag", "true", Some("default")),
    ///             ("opt", "channal", Some("chan")),
    ///         ]))
    ///     .get_matches_from(vec![
    ///         "prog", "--opt", "channal"
    ///     ]);
    ///
    /// assert_eq!(m.get_one::<String>("other").unwrap(), "chan");
    /// ```
    ///
    /// Next we run the same test, but without providing `--flag`.
    ///
    /// ```rust
    /// # use clap::{Command, Arg, ArgAction};
    /// let m = Command::new("prog")
    ///     .arg(Arg::new("flag")
    ///         .long("flag")
    ///         .action(ArgAction::SetTrue))
    ///     .arg(Arg::new("other")
    ///         .long("other")
    ///         .default_value_ifs([
    ///             ("flag", "true", Some("default")),
    ///             ("opt", "channal", Some("chan")),
    ///         ]))
    ///     .get_matches_from(vec![
    ///         "prog"
    ///     ]);
    ///
    /// assert_eq!(m.get_one::<String>("other"), None);
    /// ```
    ///
    /// We can also see that these values are applied in order, and if more than one condition is
    /// true, only the first evaluated "wins"
    ///
    /// ```rust
    /// # use clap::{Command, Arg, ArgAction};
    /// # use clap::builder::ArgPredicate;
    /// let m = Command::new("prog")
    ///     .arg(Arg::new("flag")
    ///         .long("flag")
    ///         .action(ArgAction::SetTrue))
    ///     .arg(Arg::new("opt")
    ///         .long("opt")
    ///         .action(ArgAction::Set))
    ///     .arg(Arg::new("other")
    ///         .long("other")
    ///         .default_value_ifs([
    ///             ("flag", ArgPredicate::IsPresent, Some("default")),
    ///             ("opt", ArgPredicate::Equals("channal".into()), Some("chan")),
    ///         ]))
    ///     .get_matches_from(vec![
    ///         "prog", "--opt", "channal", "--flag"
    ///     ]);
    ///
    /// assert_eq!(m.get_one::<String>("other").unwrap(), "default");
    /// ```
    /// [`Arg::action(ArgAction::Set)`]: Arg::action()
    /// [`Arg::default_value_if`]: Arg::default_value_if()
    #[must_use]
    pub fn default_value_ifs(
        mut self,
        ifs: impl IntoIterator<
            Item = (
                impl Into<Id>,
                impl Into<ArgPredicate>,
                impl IntoResettable<OsStr>,
            ),
        >,
    ) -> Self {
        for (arg, predicate, default) in ifs {
            self = self.default_value_if(arg, predicate, default);
        }
        self
    }

pub fn default_value_ifs(
    self,
    ifs: impl IntoIterator<Item = (impl Into<Id>, impl Into<ArgPredicate>, impl IntoResettable<OsStr>)>
) -> Self

Specifies multiple values and conditions in the same manner as Arg::default_value_if.

The method takes a slice of tuples in the (arg, predicate, default) format.

NOTE: The conditions are stored in order and evaluated in the same order. I.e. the first if multiple conditions are true, the first one found will be applied and the ultimate value.

Examples

First we use the default value only if another arg is present at runtime.

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("opt")
        .long("opt")
        .action(ArgAction::Set))
    .arg(Arg::new("other")
        .long("other")
        .default_value_ifs([
            ("flag", "true", Some("default")),
            ("opt", "channal", Some("chan")),
        ]))
    .get_matches_from(vec![
        "prog", "--opt", "channal"
    ]);

assert_eq!(m.get_one::<String>("other").unwrap(), "chan");

Next we run the same test, but without providing --flag.

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("other")
        .long("other")
        .default_value_ifs([
            ("flag", "true", Some("default")),
            ("opt", "channal", Some("chan")),
        ]))
    .get_matches_from(vec![
        "prog"
    ]);

assert_eq!(m.get_one::<String>("other"), None);

We can also see that these values are applied in order, and if more than one condition is true, only the first evaluated “wins”

let m = Command::new("prog")
    .arg(Arg::new("flag")
        .long("flag")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("opt")
        .long("opt")
        .action(ArgAction::Set))
    .arg(Arg::new("other")
        .long("other")
        .default_value_ifs([
            ("flag", ArgPredicate::IsPresent, Some("default")),
            ("opt", ArgPredicate::Equals("channal".into()), Some("chan")),
        ]))
    .get_matches_from(vec![
        "prog", "--opt", "channal", "--flag"
    ]);

assert_eq!(m.get_one::<String>("other").unwrap(), "default");

Examples found in repository

src/builder/arg.rs (line 2892)

    pub fn default_value_ifs_os(
        self,
        ifs: impl IntoIterator<
            Item = (
                impl Into<Id>,
                impl Into<ArgPredicate>,
                impl IntoResettable<OsStr>,
            ),
        >,
    ) -> Self {
        self.default_value_ifs(ifs)
    }

pub fn required_unless_present(self, arg_id: impl IntoResettable<Id>) -> Self

Set this arg as required as long as the specified argument is not present at runtime.

Pro Tip: Using Arg::required_unless_present implies Arg::required and is therefore not mandatory to also set.

Examples

Arg::new("config")
    .required_unless_present("debug")

In the following example, the required argument is not provided, but it’s not an error because the unless arg has been supplied.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present("dbg")
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug")
        .action(ArgAction::SetTrue))
    .try_get_matches_from(vec![
        "prog", "--debug"
    ]);

assert!(res.is_ok());

Setting Arg::required_unless_present(name) and not supplying name or this arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present("dbg")
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug"))
    .try_get_matches_from(vec![
        "prog"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn required_unless_present_all(
    self,
    names: impl IntoIterator<Item = impl Into<Id>>
) -> Self

Sets this arg as required unless all of the specified arguments are present at runtime.

In other words, parsing will succeed only if user either

• supplies the self arg.
• supplies all of the names arguments.

NOTE: If you wish for this argument to only be required unless any of these args are present see Arg::required_unless_present_any

Examples

Arg::new("config")
    .required_unless_present_all(["cfg", "dbg"])

In the following example, the required argument is not provided, but it’s not an error because all of the names args have been supplied.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present_all(["dbg", "infile"])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("infile")
        .short('i')
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--debug", "-i", "file"
    ]);

assert!(res.is_ok());

Setting Arg::required_unless_present_all(names) and not supplying either all of unless args or the self arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present_all(["dbg", "infile"])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("infile")
        .short('i')
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn required_unless_present_any(
    self,
    names: impl IntoIterator<Item = impl Into<Id>>
) -> Self

Sets this arg as required unless any of the specified arguments are present at runtime.

In other words, parsing will succeed only if user either

• supplies the self arg.
• supplies one or more of the unless arguments.

NOTE: If you wish for this argument to be required unless all of these args are present see Arg::required_unless_present_all

Examples

Arg::new("config")
    .required_unless_present_any(["cfg", "dbg"])

Setting Arg::required_unless_present_any(names) requires that the argument be used at runtime unless at least one of the args in names are present. In the following example, the required argument is not provided, but it’s not an error because one the unless args have been supplied.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present_any(["dbg", "infile"])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("infile")
        .short('i')
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--debug"
    ]);

assert!(res.is_ok());

Setting Arg::required_unless_present_any(names) and not supplying at least one of names or this arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_unless_present_any(["dbg", "infile"])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("dbg")
        .long("debug")
        .action(ArgAction::SetTrue))
    .arg(Arg::new("infile")
        .short('i')
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn required_if_eq(self, arg_id: impl Into<Id>, val: impl Into<OsStr>) -> Self

This argument is required only if the specified arg is present at runtime and its value equals val.

Examples

Arg::new("config")
    .required_if_eq("other_arg", "value")

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .required_if_eq("other", "special")
        .long("config"))
    .arg(Arg::new("other")
        .long("other")
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--other", "not-special"
    ]);

assert!(res.is_ok()); // We didn't use --other=special, so "cfg" wasn't required

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .required_if_eq("other", "special")
        .long("config"))
    .arg(Arg::new("other")
        .long("other")
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--other", "special"
    ]);

// We did use --other=special so "cfg" had become required but was missing.
assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .required_if_eq("other", "special")
        .long("config"))
    .arg(Arg::new("other")
        .long("other")
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--other", "SPECIAL"
    ]);

// By default, the comparison is case-sensitive, so "cfg" wasn't required
assert!(res.is_ok());

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .required_if_eq("other", "special")
        .long("config"))
    .arg(Arg::new("other")
        .long("other")
        .ignore_case(true)
        .action(ArgAction::Set))
    .try_get_matches_from(vec![
        "prog", "--other", "SPECIAL"
    ]);

// However, case-insensitive comparisons can be enabled.  This typically occurs when using Arg::possible_values().
assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn required_if_eq_any(
    self,
    ifs: impl IntoIterator<Item = (impl Into<Id>, impl Into<OsStr>)>
) -> Self

Specify this argument is required based on multiple conditions.

The conditions are set up in a (arg, val) style tuple. The requirement will only become valid if one of the specified arg’s value equals its corresponding val.

Examples

Arg::new("config")
    .required_if_eq_any([
        ("extra", "val"),
        ("option", "spec")
    ])

Setting Arg::required_if_eq_any([(arg, val)]) makes this arg required if any of the args are used at runtime and it’s corresponding value is equal to val. If the arg’s value is anything other than val, this argument isn’t required.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_if_eq_any([
            ("extra", "val"),
            ("option", "spec")
        ])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("extra")
        .action(ArgAction::Set)
        .long("extra"))
    .arg(Arg::new("option")
        .action(ArgAction::Set)
        .long("option"))
    .try_get_matches_from(vec![
        "prog", "--option", "other"
    ]);

assert!(res.is_ok()); // We didn't use --option=spec, or --extra=val so "cfg" isn't required

Setting Arg::required_if_eq_any([(arg, val)]) and having any of the args used with its value of val but not using this arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_if_eq_any([
            ("extra", "val"),
            ("option", "spec")
        ])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("extra")
        .action(ArgAction::Set)
        .long("extra"))
    .arg(Arg::new("option")
        .action(ArgAction::Set)
        .long("option"))
    .try_get_matches_from(vec![
        "prog", "--option", "spec"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn required_if_eq_all(
    self,
    ifs: impl IntoIterator<Item = (impl Into<Id>, impl Into<OsStr>)>
) -> Self

Specify this argument is required based on multiple conditions.

The conditions are set up in a (arg, val) style tuple. The requirement will only become valid if every one of the specified arg’s value equals its corresponding val.

Examples

Arg::new("config")
    .required_if_eq_all([
        ("extra", "val"),
        ("option", "spec")
    ])

Setting Arg::required_if_eq_all([(arg, val)]) makes this arg required if all of the args are used at runtime and every value is equal to its corresponding val. If the arg’s value is anything other than val, this argument isn’t required.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_if_eq_all([
            ("extra", "val"),
            ("option", "spec")
        ])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("extra")
        .action(ArgAction::Set)
        .long("extra"))
    .arg(Arg::new("option")
        .action(ArgAction::Set)
        .long("option"))
    .try_get_matches_from(vec![
        "prog", "--option", "spec"
    ]);

assert!(res.is_ok()); // We didn't use --option=spec --extra=val so "cfg" isn't required

Setting Arg::required_if_eq_all([(arg, val)]) and having all of the args used with its value of val but not using this arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .required_if_eq_all([
            ("extra", "val"),
            ("option", "spec")
        ])
        .action(ArgAction::Set)
        .long("config"))
    .arg(Arg::new("extra")
        .action(ArgAction::Set)
        .long("extra"))
    .arg(Arg::new("option")
        .action(ArgAction::Set)
        .long("option"))
    .try_get_matches_from(vec![
        "prog", "--extra", "val", "--option", "spec"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn requires_if(
    self,
    val: impl Into<ArgPredicate>,
    arg_id: impl Into<Id>
) -> Self

Require another argument if this arg matches the ArgPredicate

This method takes value, another_arg pair. At runtime, clap will check if this arg (self) matches the ArgPredicate. If it does, another_arg will be marked as required.

Examples

Arg::new("config")
    .requires_if("val", "arg")

Setting Arg::requires_if(val, arg) requires that the arg be used at runtime if the defining argument’s value is equal to val. If the defining argument is anything other than val, the other argument isn’t required.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires_if("my.cfg", "other")
        .long("config"))
    .arg(Arg::new("other"))
    .try_get_matches_from(vec![
        "prog", "--config", "some.cfg"
    ]);

assert!(res.is_ok()); // We didn't use --config=my.cfg, so other wasn't required

Setting Arg::requires_if(val, arg) and setting the value to val but not supplying arg is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires_if("my.cfg", "input")
        .long("config"))
    .arg(Arg::new("input"))
    .try_get_matches_from(vec![
        "prog", "--config", "my.cfg"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

pub fn requires_ifs(
    self,
    ifs: impl IntoIterator<Item = (impl Into<ArgPredicate>, impl Into<Id>)>
) -> Self

Allows multiple conditional requirements.

The requirement will only become valid if this arg’s value matches the ArgPredicate.

Examples

Arg::new("config")
    .requires_ifs([
        ("val", "arg"),
        ("other_val", "arg2"),
    ])

Setting Arg::requires_ifs(["val", "arg"]) requires that the arg be used at runtime if the defining argument’s value is equal to val. If the defining argument’s value is anything other than val, arg isn’t required.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires_ifs([
            ("special.conf", "opt"),
            ("other.conf", "other"),
        ])
        .long("config"))
    .arg(Arg::new("opt")
        .long("option")
        .action(ArgAction::Set))
    .arg(Arg::new("other"))
    .try_get_matches_from(vec![
        "prog", "--config", "special.conf"
    ]);

assert!(res.is_err()); // We  used --config=special.conf so --option <val> is required
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

Setting Arg::requires_ifs with ArgPredicate::IsPresent and not supplying all the arguments is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .requires_ifs([
            (ArgPredicate::IsPresent, "input"),
            (ArgPredicate::IsPresent, "output"),
        ])
        .long("config"))
    .arg(Arg::new("input"))
    .arg(Arg::new("output"))
    .try_get_matches_from(vec![
        "prog", "--config", "file.conf", "in.txt"
    ]);

assert!(res.is_err());
// We didn't use output
assert_eq!(res.unwrap_err().kind(), ErrorKind::MissingRequiredArgument);

Examples found in repository

src/builder/arg.rs (line 3508)

    pub fn requires_all(self, ids: impl IntoIterator<Item = impl Into<Id>>) -> Self {
        self.requires_ifs(ids.into_iter().map(|id| (ArgPredicate::IsPresent, id)))
    }

pub fn conflicts_with(self, arg_id: impl IntoResettable<Id>) -> Self

This argument is mutually exclusive with the specified argument.

NOTE: Conflicting rules take precedence over being required by default. Conflict rules only need to be set for one of the two arguments, they do not need to be set for each.

NOTE: Defining a conflict is two-way, but does not need to defined for both arguments (i.e. if A conflicts with B, defining A.conflicts_with(B) is sufficient. You do not need to also do B.conflicts_with(A))

NOTE: Arg::conflicts_with_all(names) allows specifying an argument which conflicts with more than one argument.

NOTE Arg::exclusive(true) allows specifying an argument which conflicts with every other argument.

NOTE: All arguments implicitly conflict with themselves.

Examples

Arg::new("config")
    .conflicts_with("debug")

Setting conflicting argument, and having both arguments present at runtime is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .conflicts_with("debug")
        .long("config"))
    .arg(Arg::new("debug")
        .long("debug")
        .action(ArgAction::SetTrue))
    .try_get_matches_from(vec![
        "prog", "--debug", "--config", "file.conf"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::ArgumentConflict);

pub fn conflicts_with_all(
    self,
    names: impl IntoIterator<Item = impl Into<Id>>
) -> Self

This argument is mutually exclusive with the specified arguments.

See Arg::conflicts_with.

NOTE: Conflicting rules take precedence over being required by default. Conflict rules only need to be set for one of the two arguments, they do not need to be set for each.

NOTE: Defining a conflict is two-way, but does not need to defined for both arguments (i.e. if A conflicts with B, defining A.conflicts_with(B) is sufficient. You do not need need to also do B.conflicts_with(A))

NOTE: Arg::exclusive(true) allows specifying an argument which conflicts with every other argument.

Examples

Arg::new("config")
    .conflicts_with_all(["debug", "input"])

Setting conflicting argument, and having any of the arguments present at runtime with a conflicting argument is an error.

let res = Command::new("prog")
    .arg(Arg::new("cfg")
        .action(ArgAction::Set)
        .conflicts_with_all(["debug", "input"])
        .long("config"))
    .arg(Arg::new("debug")
        .long("debug"))
    .arg(Arg::new("input"))
    .try_get_matches_from(vec![
        "prog", "--config", "file.conf", "file.txt"
    ]);

assert!(res.is_err());
assert_eq!(res.unwrap_err().kind(), ErrorKind::ArgumentConflict);

pub fn overrides_with(self, arg_id: impl IntoResettable<Id>) -> Self

Sets an overridable argument.

i.e. this argument and the following argument will override each other in POSIX style (whichever argument was specified at runtime last “wins”)

NOTE: When an argument is overridden it is essentially as if it never was used, any conflicts, requirements, etc. are evaluated after all “overrides” have been removed

NOTE: Overriding an argument implies they conflict.

Examples

let m = Command::new("prog")
    .arg(arg!(-f --flag "some flag")
        .conflicts_with("debug"))
    .arg(arg!(-d --debug "other flag"))
    .arg(arg!(-c --color "third flag")
        .overrides_with("flag"))
    .get_matches_from(vec![
        "prog", "-f", "-d", "-c"]);
            //    ^~~~~~~~~~~~^~~~~ flag is overridden by color

assert!(*m.get_one::<bool>("color").unwrap());
assert!(*m.get_one::<bool>("debug").unwrap()); // even though flag conflicts with debug, it's as if flag
                                // was never used because it was overridden with color
assert!(!*m.get_one::<bool>("flag").unwrap());

pub fn overrides_with_all(
    self,
    names: impl IntoIterator<Item = impl Into<Id>>
) -> Self

Sets multiple mutually overridable arguments by name.

i.e. this argument and the following argument will override each other in POSIX style (whichever argument was specified at runtime last “wins”)

NOTE: When an argument is overridden it is essentially as if it never was used, any conflicts, requirements, etc. are evaluated after all “overrides” have been removed

NOTE: Overriding an argument implies they conflict.

Examples

let m = Command::new("prog")
    .arg(arg!(-f --flag "some flag")
        .conflicts_with("color"))
    .arg(arg!(-d --debug "other flag"))
    .arg(arg!(-c --color "third flag")
        .overrides_with_all(["flag", "debug"]))
    .get_matches_from(vec![
        "prog", "-f", "-d", "-c"]);
            //    ^~~~~~^~~~~~~~~ flag and debug are overridden by color

assert!(*m.get_one::<bool>("color").unwrap()); // even though flag conflicts with color, it's as if flag
                                // and debug were never used because they were overridden
                                // with color
assert!(!*m.get_one::<bool>("debug").unwrap());
assert!(!*m.get_one::<bool>("flag").unwrap());

impl Arg

Reflection

pub fn get_id(&self) -> &Id

Get the name of the argument

Examples found in repository

src/parser/arg_matcher.rs (line 28)

    pub(crate) fn new(_cmd: &Command) -> Self {
        ArgMatcher {
            matches: ArgMatches {
                #[cfg(debug_assertions)]
                valid_args: {
                    let args = _cmd.get_arguments().map(|a| a.get_id().clone());
                    let groups = _cmd.get_groups().map(|g| g.get_id().clone());
                    args.chain(groups).collect()
                },
                #[cfg(debug_assertions)]
                valid_subcommands: _cmd
                    .get_subcommands()
                    .map(|sc| sc.get_name_str().clone())
                    .collect(),
                ..Default::default()
            },
            pending: None,
        }
    }

    pub(crate) fn into_inner(self) -> ArgMatches {
        self.matches
    }

    pub(crate) fn propagate_globals(&mut self, global_arg_vec: &[Id]) {
        debug!(
            "ArgMatcher::get_global_values: global_arg_vec={:?}",
            global_arg_vec
        );
        let mut vals_map = FlatMap::new();
        self.fill_in_global_values(global_arg_vec, &mut vals_map);
    }

    fn fill_in_global_values(
        &mut self,
        global_arg_vec: &[Id],
        vals_map: &mut FlatMap<Id, MatchedArg>,
    ) {
        for global_arg in global_arg_vec {
            if let Some(ma) = self.get(global_arg) {
                // We have to check if the parent's global arg wasn't used but still exists
                // such as from a default value.
                //
                // For example, `myprog subcommand --global-arg=value` where `--global-arg` defines
                // a default value of `other` myprog would have an existing MatchedArg for
                // `--global-arg` where the value is `other`
                let to_update = if let Some(parent_ma) = vals_map.get(global_arg) {
                    if parent_ma.source() > ma.source() {
                        parent_ma
                    } else {
                        ma
                    }
                } else {
                    ma
                }
                .clone();
                vals_map.insert(global_arg.clone(), to_update);
            }
        }
        if let Some(ref mut sc) = self.matches.subcommand {
            let mut am = ArgMatcher {
                matches: mem::take(&mut sc.matches),
                pending: None,
            };
            am.fill_in_global_values(global_arg_vec, vals_map);
            mem::swap(&mut am.matches, &mut sc.matches);
        }

        for (name, matched_arg) in vals_map.iter_mut() {
            self.matches.args.insert(name.clone(), matched_arg.clone());
        }
    }

    pub(crate) fn get(&self, arg: &Id) -> Option<&MatchedArg> {
        self.matches.args.get(arg)
    }

    pub(crate) fn get_mut(&mut self, arg: &Id) -> Option<&mut MatchedArg> {
        self.matches.args.get_mut(arg)
    }

    pub(crate) fn remove(&mut self, arg: &Id) -> bool {
        self.matches.args.remove(arg).is_some()
    }

    pub(crate) fn contains(&self, arg: &Id) -> bool {
        self.matches.args.contains_key(arg)
    }

    pub(crate) fn arg_ids(&self) -> std::slice::Iter<'_, Id> {
        self.matches.args.keys()
    }

    pub(crate) fn entry(&mut self, arg: Id) -> crate::util::Entry<Id, MatchedArg> {
        self.matches.args.entry(arg)
    }

    pub(crate) fn subcommand(&mut self, sc: SubCommand) {
        self.matches.subcommand = Some(Box::new(sc));
    }

    pub(crate) fn subcommand_name(&self) -> Option<&str> {
        self.matches.subcommand_name()
    }

    pub(crate) fn check_explicit(&self, arg: &Id, predicate: &ArgPredicate) -> bool {
        self.get(arg).map_or(false, |a| a.check_explicit(predicate))
    }

    pub(crate) fn start_custom_arg(&mut self, arg: &Arg, source: ValueSource) {
        let id = arg.get_id().clone();
        debug!(
            "ArgMatcher::start_custom_arg: id={:?}, source={:?}",
            id, source
        );
        let ma = self.entry(id).or_insert(MatchedArg::new_arg(arg));
        debug_assert_eq!(ma.type_id(), Some(arg.get_value_parser().type_id()));
        ma.set_source(source);
        ma.new_val_group();
    }

    pub(crate) fn start_custom_group(&mut self, id: Id, source: ValueSource) {
        debug!(
            "ArgMatcher::start_custom_arg: id={:?}, source={:?}",
            id, source
        );
        let ma = self.entry(id).or_insert(MatchedArg::new_group());
        debug_assert_eq!(ma.type_id(), None);
        ma.set_source(source);
        ma.new_val_group();
    }

    pub(crate) fn start_occurrence_of_external(&mut self, cmd: &crate::Command) {
        let id = Id::from_static_ref(Id::EXTERNAL);
        debug!("ArgMatcher::start_occurrence_of_external: id={:?}", id,);
        let ma = self.entry(id).or_insert(MatchedArg::new_external(cmd));
        debug_assert_eq!(
            ma.type_id(),
            Some(
                cmd.get_external_subcommand_value_parser()
                    .expect(INTERNAL_ERROR_MSG)
                    .type_id()
            )
        );
        ma.set_source(ValueSource::CommandLine);
        ma.new_val_group();
    }

    pub(crate) fn add_val_to(&mut self, arg: &Id, val: AnyValue, raw_val: OsString) {
        let ma = self.get_mut(arg).expect(INTERNAL_ERROR_MSG);
        ma.append_val(val, raw_val);
    }

    pub(crate) fn add_index_to(&mut self, arg: &Id, idx: usize) {
        let ma = self.get_mut(arg).expect(INTERNAL_ERROR_MSG);
        ma.push_index(idx);
    }

    pub(crate) fn needs_more_vals(&self, o: &Arg) -> bool {
        let num_pending = self
            .pending
            .as_ref()
            .and_then(|p| (p.id == *o.get_id()).then(|| p.raw_vals.len()))
            .unwrap_or(0);
        debug!(
            "ArgMatcher::needs_more_vals: o={}, pending={}",
            o.get_id(),
            num_pending
        );
        let expected = o.get_num_args().expect(INTERNAL_ERROR_MSG);
        debug!(
            "ArgMatcher::needs_more_vals: expected={}, actual={}",
            expected, num_pending
        );
        expected.accepts_more(num_pending)
    }

src/builder/command.rs (line 3523)

    fn get_global_arg_conflicts_with(&self, arg: &Arg) -> Vec<&Arg> // FIXME: This could probably have been an iterator
    {
        arg.blacklist
            .iter()
            .map(|id| {
                self.args
                    .args()
                    .chain(
                        self.get_subcommands_containing(arg)
                            .iter()
                            .flat_map(|x| x.args.args()),
                    )
                    .find(|arg| arg.get_id() == id)
                    .expect(
                        "Command::get_arg_conflicts_with: \
                    The passed arg conflicts with an arg unknown to the cmd",
                    )
            })
            .collect()
    }

    // Get a list of subcommands which contain the provided Argument
    //
    // This command will only include subcommands in its list for which the subcommands
    // parent also contains the Argument.
    //
    // This search follows the propagation rules of global arguments.
    // It is useful to finding subcommands, that have inherited a global argument.
    //
    // **NOTE:** In this case only Sucommand_1 will be included
    //   Subcommand_1 (contains Arg)
    //     Subcommand_1.1 (doesn't contain Arg)
    //       Subcommand_1.1.1 (contains Arg)
    //
    fn get_subcommands_containing(&self, arg: &Arg) -> Vec<&Self> {
        let mut vec = std::vec::Vec::new();
        for idx in 0..self.subcommands.len() {
            if self.subcommands[idx]
                .args
                .args()
                .any(|ar| ar.get_id() == arg.get_id())
            {
                vec.push(&self.subcommands[idx]);
                vec.append(&mut self.subcommands[idx].get_subcommands_containing(arg));
            }
        }
        vec
    }

    /// Report whether [`Command::no_binary_name`] is set
    pub fn is_no_binary_name_set(&self) -> bool {
        self.is_set(AppSettings::NoBinaryName)
    }

    /// Report whether [`Command::ignore_errors`] is set
    pub(crate) fn is_ignore_errors_set(&self) -> bool {
        self.is_set(AppSettings::IgnoreErrors)
    }

    /// Report whether [`Command::dont_delimit_trailing_values`] is set
    pub fn is_dont_delimit_trailing_values_set(&self) -> bool {
        self.is_set(AppSettings::DontDelimitTrailingValues)
    }

    /// Report whether [`Command::disable_version_flag`] is set
    pub fn is_disable_version_flag_set(&self) -> bool {
        self.is_set(AppSettings::DisableVersionFlag)
            || (self.version.is_none() && self.long_version.is_none())
    }

    /// Report whether [`Command::propagate_version`] is set
    pub fn is_propagate_version_set(&self) -> bool {
        self.is_set(AppSettings::PropagateVersion)
    }

    /// Report whether [`Command::next_line_help`] is set
    pub fn is_next_line_help_set(&self) -> bool {
        self.is_set(AppSettings::NextLineHelp)
    }

    /// Report whether [`Command::disable_help_flag`] is set
    pub fn is_disable_help_flag_set(&self) -> bool {
        self.is_set(AppSettings::DisableHelpFlag)
    }

    /// Report whether [`Command::disable_help_subcommand`] is set
    pub fn is_disable_help_subcommand_set(&self) -> bool {
        self.is_set(AppSettings::DisableHelpSubcommand)
    }

    /// Report whether [`Command::disable_colored_help`] is set
    pub fn is_disable_colored_help_set(&self) -> bool {
        self.is_set(AppSettings::DisableColoredHelp)
    }

    /// Report whether [`Command::help_expected`] is set
    #[cfg(debug_assertions)]
    pub(crate) fn is_help_expected_set(&self) -> bool {
        self.is_set(AppSettings::HelpExpected)
    }

    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(since = "4.0.0", note = "This is now the default")
    )]
    pub fn is_dont_collapse_args_in_usage_set(&self) -> bool {
        true
    }

    /// Report whether [`Command::infer_long_args`] is set
    pub(crate) fn is_infer_long_args_set(&self) -> bool {
        self.is_set(AppSettings::InferLongArgs)
    }

    /// Report whether [`Command::infer_subcommands`] is set
    pub(crate) fn is_infer_subcommands_set(&self) -> bool {
        self.is_set(AppSettings::InferSubcommands)
    }

    /// Report whether [`Command::arg_required_else_help`] is set
    pub fn is_arg_required_else_help_set(&self) -> bool {
        self.is_set(AppSettings::ArgRequiredElseHelp)
    }

    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(
            since = "4.0.0",
            note = "Replaced with `Arg::is_allow_hyphen_values_set`"
        )
    )]
    pub(crate) fn is_allow_hyphen_values_set(&self) -> bool {
        self.is_set(AppSettings::AllowHyphenValues)
    }

    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(
            since = "4.0.0",
            note = "Replaced with `Arg::is_allow_negative_numbers_set`"
        )
    )]
    pub fn is_allow_negative_numbers_set(&self) -> bool {
        self.is_set(AppSettings::AllowNegativeNumbers)
    }

    #[doc(hidden)]
    #[cfg_attr(
        feature = "deprecated",
        deprecated(since = "4.0.0", note = "Replaced with `Arg::is_trailing_var_arg_set`")
    )]
    pub fn is_trailing_var_arg_set(&self) -> bool {
        self.is_set(AppSettings::TrailingVarArg)
    }

    /// Report whether [`Command::allow_missing_positional`] is set
    pub fn is_allow_missing_positional_set(&self) -> bool {
        self.is_set(AppSettings::AllowMissingPositional)
    }

    /// Report whether [`Command::hide`] is set
    pub fn is_hide_set(&self) -> bool {
        self.is_set(AppSettings::Hidden)
    }

    /// Report whether [`Command::subcommand_required`] is set
    pub fn is_subcommand_required_set(&self) -> bool {
        self.is_set(AppSettings::SubcommandRequired)
    }

    /// Report whether [`Command::allow_external_subcommands`] is set
    pub fn is_allow_external_subcommands_set(&self) -> bool {
        self.is_set(AppSettings::AllowExternalSubcommands)
    }

    /// Configured parser for values passed to an external subcommand
    ///
    /// # Example
    ///
    /// ```rust
    /// let cmd = clap::Command::new("raw")
    ///     .external_subcommand_value_parser(clap::value_parser!(String));
    /// let value_parser = cmd.get_external_subcommand_value_parser();
    /// println!("{:?}", value_parser);
    /// ```
    pub fn get_external_subcommand_value_parser(&self) -> Option<&super::ValueParser> {
        if !self.is_allow_external_subcommands_set() {
            None
        } else {
            static DEFAULT: super::ValueParser = super::ValueParser::os_string();
            Some(self.external_value_parser.as_ref().unwrap_or(&DEFAULT))
        }
    }

    /// Report whether [`Command::args_conflicts_with_subcommands`] is set
    pub fn is_args_conflicts_with_subcommands_set(&self) -> bool {
        self.is_set(AppSettings::ArgsNegateSubcommands)
    }

    #[doc(hidden)]
    pub fn is_args_override_self(&self) -> bool {
        self.is_set(AppSettings::AllArgsOverrideSelf)
    }

    /// Report whether [`Command::subcommand_precedence_over_arg`] is set
    pub fn is_subcommand_precedence_over_arg_set(&self) -> bool {
        self.is_set(AppSettings::SubcommandPrecedenceOverArg)
    }

    /// Report whether [`Command::subcommand_negates_reqs`] is set
    pub fn is_subcommand_negates_reqs_set(&self) -> bool {
        self.is_set(AppSettings::SubcommandsNegateReqs)
    }

    /// Report whether [`Command::multicall`] is set
    pub fn is_multicall_set(&self) -> bool {
        self.is_set(AppSettings::Multicall)
    }
}

// Internally used only
impl Command {
    pub(crate) fn get_override_usage(&self) -> Option<&StyledStr> {
        self.usage_str.as_ref()
    }

    pub(crate) fn get_override_help(&self) -> Option<&StyledStr> {
        self.help_str.as_ref()
    }

    #[cfg(feature = "help")]
    pub(crate) fn get_help_template(&self) -> Option<&StyledStr> {
        self.template.as_ref()
    }

    #[cfg(feature = "help")]
    pub(crate) fn get_term_width(&self) -> Option<usize> {
        self.term_w
    }

    #[cfg(feature = "help")]
    pub(crate) fn get_max_term_width(&self) -> Option<usize> {
        self.max_w
    }

    pub(crate) fn get_replacement(&self, key: &str) -> Option<&[Str]> {
        self.replacers.get(key).map(|v| v.as_slice())
    }

    pub(crate) fn get_keymap(&self) -> &MKeyMap {
        &self.args
    }

    fn get_used_global_args(&self, matches: &ArgMatches, global_arg_vec: &mut Vec<Id>) {
        global_arg_vec.extend(
            self.args
                .args()
                .filter(|a| a.is_global_set())
                .map(|ga| ga.id.clone()),
        );
        if let Some((id, matches)) = matches.subcommand() {
            if let Some(used_sub) = self.find_subcommand(id) {
                used_sub.get_used_global_args(matches, global_arg_vec);
            }
        }
    }

    fn _do_parse(
        &mut self,
        raw_args: &mut clap_lex::RawArgs,
        args_cursor: clap_lex::ArgCursor,
    ) -> ClapResult<ArgMatches> {
        debug!("Command::_do_parse");

        // If there are global arguments, or settings we need to propagate them down to subcommands
        // before parsing in case we run into a subcommand
        self._build_self(false);

        let mut matcher = ArgMatcher::new(self);

        // do the real parsing
        let mut parser = Parser::new(self);
        if let Err(error) = parser.get_matches_with(&mut matcher, raw_args, args_cursor) {
            if self.is_set(AppSettings::IgnoreErrors) {
                debug!("Command::_do_parse: ignoring error: {}", error);
            } else {
                return Err(error);
            }
        }

        let mut global_arg_vec = Default::default();
        self.get_used_global_args(&matcher, &mut global_arg_vec);

        matcher.propagate_globals(&global_arg_vec);

        Ok(matcher.into_inner())
    }

    /// Prepare for introspecting on all included [`Command`]s
    ///
    /// Call this on the top-level [`Command`] when done building and before reading state for
    /// cases like completions, custom help output, etc.
    pub fn build(&mut self) {
        self._build_recursive(true);
        self._build_bin_names_internal();
    }

    pub(crate) fn _build_recursive(&mut self, expand_help_tree: bool) {
        self._build_self(expand_help_tree);
        for subcmd in self.get_subcommands_mut() {
            subcmd._build_recursive(expand_help_tree);
        }
    }

    pub(crate) fn _build_self(&mut self, expand_help_tree: bool) {
        debug!("Command::_build: name={:?}", self.get_name());
        if !self.settings.is_set(AppSettings::Built) {
            // Make sure all the globally set flags apply to us as well
            self.settings = self.settings | self.g_settings;

            if self.is_multicall_set() {
                self.settings.insert(AppSettings::SubcommandRequired.into());
                self.settings.insert(AppSettings::DisableHelpFlag.into());
                self.settings.insert(AppSettings::DisableVersionFlag.into());
            }
            if !cfg!(feature = "help") && self.get_override_help().is_none() {
                self.settings.insert(AppSettings::DisableHelpFlag.into());
                self.settings
                    .insert(AppSettings::DisableHelpSubcommand.into());
            }
            if self.is_set(AppSettings::ArgsNegateSubcommands) {
                self.settings
                    .insert(AppSettings::SubcommandsNegateReqs.into());
            }
            if self.external_value_parser.is_some() {
                self.settings
                    .insert(AppSettings::AllowExternalSubcommands.into());
            }
            if !self.has_subcommands() {
                self.settings
                    .insert(AppSettings::DisableHelpSubcommand.into());
            }

            self._propagate();
            self._check_help_and_version(expand_help_tree);
            self._propagate_global_args();

            let mut pos_counter = 1;
            let hide_pv = self.is_set(AppSettings::HidePossibleValues);
            for a in self.args.args_mut() {
                // Fill in the groups
                for g in &a.groups {
                    if let Some(ag) = self.groups.iter_mut().find(|grp| grp.id == *g) {
                        ag.args.push(a.get_id().clone());
                    } else {
                        let mut ag = ArgGroup::new(g);
                        ag.args.push(a.get_id().clone());
                        self.groups.push(ag);
                    }
                }

                // Figure out implied settings
                a._build();
                if hide_pv && a.is_takes_value_set() {
                    a.settings.set(ArgSettings::HidePossibleValues);
                }
                if a.is_positional() && a.index.is_none() {
                    a.index = Some(pos_counter);
                    pos_counter += 1;
                }
            }

            self.args._build();

            #[allow(deprecated)]
            {
                let highest_idx = self
                    .get_keymap()
                    .keys()
                    .filter_map(|x| {
                        if let crate::mkeymap::KeyType::Position(n) = x {
                            Some(*n)
                        } else {
                            None
                        }
                    })
                    .max()
                    .unwrap_or(0);
                let is_trailing_var_arg_set = self.is_trailing_var_arg_set();
                let is_allow_hyphen_values_set = self.is_allow_hyphen_values_set();
                let is_allow_negative_numbers_set = self.is_allow_negative_numbers_set();
                for arg in self.args.args_mut() {
                    if is_allow_hyphen_values_set && arg.is_takes_value_set() {
                        arg.settings.insert(ArgSettings::AllowHyphenValues.into());
                    }
                    if is_allow_negative_numbers_set && arg.is_takes_value_set() {
                        arg.settings
                            .insert(ArgSettings::AllowNegativeNumbers.into());
                    }
                    if is_trailing_var_arg_set && arg.get_index() == Some(highest_idx) {
                        arg.settings.insert(ArgSettings::TrailingVarArg.into());
                    }
                }
            }

            #[cfg(debug_assertions)]
            assert_app(self);
            self.settings.set(AppSettings::Built);
        } else {
            debug!("Command::_build: already built");
        }
    }

    pub(crate) fn _build_subcommand(&mut self, name: &str) -> Option<&mut Self> {
        use std::fmt::Write;

        let mut mid_string = String::from(" ");
        #[cfg(feature = "usage")]
        if !self.is_subcommand_negates_reqs_set() && !self.is_args_conflicts_with_subcommands_set()
        {
            let reqs = Usage::new(self).get_required_usage_from(&[], None, true); // maybe Some(m)

            for s in &reqs {
                mid_string.push_str(&s.to_string());
                mid_string.push(' ');
            }
        }
        let is_multicall_set = self.is_multicall_set();

        let sc = some!(self.subcommands.iter_mut().find(|s| s.name == name));

        // Display subcommand name, short and long in usage
        let mut sc_names = String::new();
        sc_names.push_str(sc.name.as_str());
        let mut flag_subcmd = false;
        if let Some(l) = sc.get_long_flag() {
            write!(sc_names, "|--{}", l).unwrap();
            flag_subcmd = true;
        }
        if let Some(s) = sc.get_short_flag() {
            write!(sc_names, "|-{}", s).unwrap();
            flag_subcmd = true;
        }

        if flag_subcmd {
            sc_names = format!("{{{}}}", sc_names);
        }

        let usage_name = self
            .bin_name
            .as_ref()
            .map(|bin_name| format!("{}{}{}", bin_name, mid_string, sc_names))
            .unwrap_or(sc_names);
        sc.usage_name = Some(usage_name);

        // bin_name should be parent's bin_name + [<reqs>] + the sc's name separated by
        // a space
        let bin_name = format!(
            "{}{}{}",
            self.bin_name.as_deref().unwrap_or_default(),
            if self.bin_name.is_some() { " " } else { "" },
            &*sc.name
        );
        debug!(
            "Command::_build_subcommand Setting bin_name of {} to {:?}",
            sc.name, bin_name
        );
        sc.bin_name = Some(bin_name);

        if sc.display_name.is_none() {
            let self_display_name = if is_multicall_set {
                self.display_name.as_deref().unwrap_or("")
            } else {
                self.display_name.as_deref().unwrap_or(&self.name)
            };
            let display_name = format!(
                "{}{}{}",
                self_display_name,
                if !self_display_name.is_empty() {
                    "-"
                } else {
                    ""
                },
                &*sc.name
            );
            debug!(
                "Command::_build_subcommand Setting display_name of {} to {:?}",
                sc.name, display_name
            );
            sc.display_name = Some(display_name);
        }

        // Ensure all args are built and ready to parse
        sc._build_self(false);

        Some(sc)
    }

    fn _build_bin_names_internal(&mut self) {
        debug!("Command::_build_bin_names");

        if !self.is_set(AppSettings::BinNameBuilt) {
            let mut mid_string = String::from(" ");
            #[cfg(feature = "usage")]
            if !self.is_subcommand_negates_reqs_set()
                && !self.is_args_conflicts_with_subcommands_set()
            {
                let reqs = Usage::new(self).get_required_usage_from(&[], None, true); // maybe Some(m)

                for s in &reqs {
                    mid_string.push_str(&s.to_string());
                    mid_string.push(' ');
                }
            }
            let is_multicall_set = self.is_multicall_set();

            let self_bin_name = if is_multicall_set {
                self.bin_name.as_deref().unwrap_or("")
            } else {
                self.bin_name.as_deref().unwrap_or(&self.name)
            }
            .to_owned();

            for mut sc in &mut self.subcommands {
                debug!("Command::_build_bin_names:iter: bin_name set...");

                if sc.usage_name.is_none() {
                    use std::fmt::Write;
                    // Display subcommand name, short and long in usage
                    let mut sc_names = String::new();
                    sc_names.push_str(sc.name.as_str());
                    let mut flag_subcmd = false;
                    if let Some(l) = sc.get_long_flag() {
                        write!(sc_names, "|--{}", l).unwrap();
                        flag_subcmd = true;
                    }
                    if let Some(s) = sc.get_short_flag() {
                        write!(sc_names, "|-{}", s).unwrap();
                        flag_subcmd = true;
                    }

                    if flag_subcmd {
                        sc_names = format!("{{{}}}", sc_names);
                    }

                    let usage_name = format!("{}{}{}", self_bin_name, mid_string, sc_names);
                    debug!(
                        "Command::_build_bin_names:iter: Setting usage_name of {} to {:?}",
                        sc.name, usage_name
                    );
                    sc.usage_name = Some(usage_name);
                } else {
                    debug!(
                        "Command::_build_bin_names::iter: Using existing usage_name of {} ({:?})",
                        sc.name, sc.usage_name
                    );
                }

                if sc.bin_name.is_none() {
                    let bin_name = format!(
                        "{}{}{}",
                        self_bin_name,
                        if !self_bin_name.is_empty() { " " } else { "" },
                        &*sc.name
                    );
                    debug!(
                        "Command::_build_bin_names:iter: Setting bin_name of {} to {:?}",
                        sc.name, bin_name
                    );
                    sc.bin_name = Some(bin_name);
                } else {
                    debug!(
                        "Command::_build_bin_names::iter: Using existing bin_name of {} ({:?})",
                        sc.name, sc.bin_name
                    );
                }

                if sc.display_name.is_none() {
                    let self_display_name = if is_multicall_set {
                        self.display_name.as_deref().unwrap_or("")
                    } else {
                        self.display_name.as_deref().unwrap_or(&self.name)
                    };
                    let display_name = format!(
                        "{}{}{}",
                        self_display_name,
                        if !self_display_name.is_empty() {
                            "-"
                        } else {
                            ""
                        },
                        &*sc.name
                    );
                    debug!(
                        "Command::_build_bin_names:iter: Setting display_name of {} to {:?}",
                        sc.name, display_name
                    );
                    sc.display_name = Some(display_name);
                } else {
                    debug!(
                        "Command::_build_bin_names::iter: Using existing display_name of {} ({:?})",
                        sc.name, sc.display_name
                    );
                }

                sc._build_bin_names_internal();
            }
            self.set(AppSettings::BinNameBuilt);
        } else {
            debug!("Command::_build_bin_names: already built");
        }
    }

    pub(crate) fn _panic_on_missing_help(&self, help_required_globally: bool) {
        if self.is_set(AppSettings::HelpExpected) || help_required_globally {
            let args_missing_help: Vec<Id> = self
                .args
                .args()
                .filter(|arg| arg.get_help().is_none() && arg.get_long_help().is_none())
                .map(|arg| arg.get_id().clone())
                .collect();

            debug_assert!(args_missing_help.is_empty(),
                    "Command::help_expected is enabled for the Command {}, but at least one of its arguments does not have either `help` or `long_help` set. List of such arguments: {}",
                    self.name,
                    args_missing_help.join(", ")
                );
        }

        for sub_app in &self.subcommands {
            sub_app._panic_on_missing_help(help_required_globally);
        }
    }

    #[cfg(debug_assertions)]
    pub(crate) fn two_args_of<F>(&self, condition: F) -> Option<(&Arg, &Arg)>
    where
        F: Fn(&Arg) -> bool,
    {
        two_elements_of(self.args.args().filter(|a: &&Arg| condition(a)))
    }

    // just in case
    #[allow(unused)]
    fn two_groups_of<F>(&self, condition: F) -> Option<(&ArgGroup, &ArgGroup)>
    where
        F: Fn(&ArgGroup) -> bool,
    {
        two_elements_of(self.groups.iter().filter(|a| condition(a)))
    }

    /// Propagate global args
    pub(crate) fn _propagate_global_args(&mut self) {
        debug!("Command::_propagate_global_args:{}", self.name);

        let autogenerated_help_subcommand = !self.is_disable_help_subcommand_set();

        for sc in &mut self.subcommands {
            if sc.get_name() == "help" && autogenerated_help_subcommand {
                // Avoid propagating args to the autogenerated help subtrees used in completion.
                // This prevents args from showing up during help completions like
                // `myapp help subcmd <TAB>`, which should only suggest subcommands and not args,
                // while still allowing args to show up properly on the generated help message.
                continue;
            }

            for a in self.args.args().filter(|a| a.is_global_set()) {
                if sc.find(&a.id).is_some() {
                    debug!(
                        "Command::_propagate skipping {:?} to {}, already exists",
                        a.id,
                        sc.get_name(),
                    );
                    continue;
                }

                debug!(
                    "Command::_propagate pushing {:?} to {}",
                    a.id,
                    sc.get_name(),
                );
                sc.args.push(a.clone());
            }
        }
    }

    /// Propagate settings
    pub(crate) fn _propagate(&mut self) {
        debug!("Command::_propagate:{}", self.name);
        let mut subcommands = std::mem::take(&mut self.subcommands);
        for sc in &mut subcommands {
            self._propagate_subcommand(sc);
        }
        self.subcommands = subcommands;
    }

    fn _propagate_subcommand(&self, sc: &mut Self) {
        // We have to create a new scope in order to tell rustc the borrow of `sc` is
        // done and to recursively call this method
        {
            if self.settings.is_set(AppSettings::PropagateVersion) {
                if let Some(version) = self.version.as_ref() {
                    sc.version.get_or_insert_with(|| version.clone());
                }
                if let Some(long_version) = self.long_version.as_ref() {
                    sc.long_version.get_or_insert_with(|| long_version.clone());
                }
            }

            sc.settings = sc.settings | self.g_settings;
            sc.g_settings = sc.g_settings | self.g_settings;
            sc.term_w = self.term_w;
            sc.max_w = self.max_w;
        }
    }

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

    fn _copy_subtree_for_help(&self) -> Command {
        let mut cmd = Command::new(self.name.clone())
            .hide(self.is_hide_set())
            .global_setting(AppSettings::DisableHelpFlag)
            .global_setting(AppSettings::DisableVersionFlag)
            .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));
        if self.get_about().is_some() {
            cmd = cmd.about(self.get_about().unwrap().clone());
        }
        cmd
    }

    pub(crate) fn _render_version(&self, use_long: bool) -> String {
        debug!("Command::_render_version");

        let ver = if use_long {
            self.long_version
                .as_deref()
                .or(self.version.as_deref())
                .unwrap_or_default()
        } else {
            self.version
                .as_deref()
                .or(self.long_version.as_deref())
                .unwrap_or_default()
        };
        let display_name = self.get_display_name().unwrap_or_else(|| self.get_name());
        format!("{} {}\n", display_name, ver)
    }

    pub(crate) fn format_group(&self, g: &Id) -> StyledStr {
        let g_string = self
            .unroll_args_in_group(g)
            .iter()
            .filter_map(|x| self.find(x))
            .map(|x| {
                if x.is_positional() {
                    // Print val_name for positional arguments. e.g. <file_name>
                    x.name_no_brackets()
                } else {
                    // Print usage string for flags arguments, e.g. <--help>
                    x.to_string()
                }
            })
            .collect::<Vec<_>>()
            .join("|");
        let mut styled = StyledStr::new();
        styled.none("<");
        styled.none(g_string);
        styled.none(">");
        styled
    }
}

/// A workaround:
/// <https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999>
pub(crate) trait Captures<'a> {}
impl<'a, T> Captures<'a> for T {}

// Internal Query Methods
impl Command {
    /// Iterate through the *flags* & *options* arguments.
    #[cfg(any(feature = "usage", feature = "help"))]
    pub(crate) fn get_non_positionals(&self) -> impl Iterator<Item = &Arg> {
        self.get_arguments().filter(|a| !a.is_positional())
    }

    pub(crate) fn find(&self, arg_id: &Id) -> Option<&Arg> {
        self.args.args().find(|a| a.get_id() == arg_id)
    }

    #[inline]
    pub(crate) fn contains_short(&self, s: char) -> bool {
        debug_assert!(
            self.is_set(AppSettings::Built),
            "If Command::_build hasn't been called, manually search through Arg shorts"
        );

        self.args.contains(s)
    }

    #[inline]
    pub(crate) fn set(&mut self, s: AppSettings) {
        self.settings.set(s)
    }

    #[inline]
    pub(crate) fn has_positionals(&self) -> bool {
        self.get_positionals().next().is_some()
    }

    #[cfg(any(feature = "usage", feature = "help"))]
    pub(crate) fn has_visible_subcommands(&self) -> bool {
        self.subcommands
            .iter()
            .any(|sc| sc.name != "help" && !sc.is_set(AppSettings::Hidden))
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this subcommand or is one of its aliases.
    #[inline]
    pub(crate) fn aliases_to(&self, name: impl AsRef<std::ffi::OsStr>) -> bool {
        let name = name.as_ref();
        self.get_name() == name || self.get_all_aliases().any(|alias| alias == name)
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this short flag subcommand or is one of its short flag aliases.
    #[inline]
    pub(crate) fn short_flag_aliases_to(&self, flag: char) -> bool {
        Some(flag) == self.short_flag
            || self.get_all_short_flag_aliases().any(|alias| flag == alias)
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this long flag subcommand or is one of its long flag aliases.
    #[inline]
    pub(crate) fn long_flag_aliases_to(&self, flag: &str) -> bool {
        match self.long_flag.as_ref() {
            Some(long_flag) => {
                long_flag == flag || self.get_all_long_flag_aliases().any(|alias| alias == flag)
            }
            None => self.get_all_long_flag_aliases().any(|alias| alias == flag),
        }
    }

    #[cfg(debug_assertions)]
    pub(crate) fn id_exists(&self, id: &Id) -> bool {
        self.args.args().any(|x| x.get_id() == id) || self.groups.iter().any(|x| x.id == *id)
    }

    /// Iterate through the groups this arg is member of.
    pub(crate) fn groups_for_arg<'a>(&'a self, arg: &Id) -> impl Iterator<Item = Id> + 'a {
        debug!("Command::groups_for_arg: id={:?}", arg);
        let arg = arg.clone();
        self.groups
            .iter()
            .filter(move |grp| grp.args.iter().any(|a| a == &arg))
            .map(|grp| grp.id.clone())
    }

    pub(crate) fn find_group(&self, group_id: &Id) -> Option<&ArgGroup> {
        self.groups.iter().find(|g| g.id == *group_id)
    }

    /// Iterate through all the names of all subcommands (not recursively), including aliases.
    /// Used for suggestions.
    pub(crate) fn all_subcommand_names(&self) -> impl Iterator<Item = &str> + Captures {
        self.get_subcommands().flat_map(|sc| {
            let name = sc.get_name();
            let aliases = sc.get_all_aliases();
            std::iter::once(name).chain(aliases)
        })
    }

    pub(crate) fn required_graph(&self) -> ChildGraph<Id> {
        let mut reqs = ChildGraph::with_capacity(5);
        for a in self.args.args().filter(|a| a.is_required_set()) {
            reqs.insert(a.get_id().clone());
        }
        for group in &self.groups {
            if group.required {
                let idx = reqs.insert(group.id.clone());
                for a in &group.requires {
                    reqs.insert_child(idx, a.clone());
                }
            }
        }

        reqs
    }

    pub(crate) fn unroll_args_in_group(&self, group: &Id) -> Vec<Id> {
        debug!("Command::unroll_args_in_group: group={:?}", group);
        let mut g_vec = vec![group];
        let mut args = vec![];

        while let Some(g) = g_vec.pop() {
            for n in self
                .groups
                .iter()
                .find(|grp| grp.id == *g)
                .expect(INTERNAL_ERROR_MSG)
                .args
                .iter()
            {
                debug!("Command::unroll_args_in_group:iter: entity={:?}", n);
                if !args.contains(n) {
                    if self.find(n).is_some() {
                        debug!("Command::unroll_args_in_group:iter: this is an arg");
                        args.push(n.clone())
                    } else {
                        debug!("Command::unroll_args_in_group:iter: this is a group");
                        g_vec.push(n);
                    }
                }
            }
        }

        args
    }

    pub(crate) fn unroll_arg_requires<F>(&self, func: F, arg: &Id) -> Vec<Id>
    where
        F: Fn(&(ArgPredicate, Id)) -> Option<Id>,
    {
        let mut processed = vec![];
        let mut r_vec = vec![arg];
        let mut args = vec![];

        while let Some(a) = r_vec.pop() {
            if processed.contains(&a) {
                continue;
            }

            processed.push(a);

            if let Some(arg) = self.find(a) {
                for r in arg.requires.iter().filter_map(&func) {
                    if let Some(req) = self.find(&r) {
                        if !req.requires.is_empty() {
                            r_vec.push(req.get_id())
                        }
                    }
                    args.push(r);
                }
            }
        }

        args
    }

src/builder/arg.rs (line 4130)

    pub(crate) fn name_no_brackets(&self) -> String {
        debug!("Arg::name_no_brackets:{}", self.get_id());
        let delim = " ";
        if !self.val_names.is_empty() {
            debug!("Arg::name_no_brackets: val_names={:#?}", self.val_names);

            if self.val_names.len() > 1 {
                self.val_names
                    .iter()
                    .map(|n| format!("<{}>", n))
                    .collect::<Vec<_>>()
                    .join(delim)
            } else {
                self.val_names
                    .first()
                    .expect(INTERNAL_ERROR_MSG)
                    .as_str()
                    .to_owned()
            }
        } else {
            debug!("Arg::name_no_brackets: just name");
            self.get_id().as_str().to_owned()
        }
    }

    pub(crate) fn stylized(&self, required: Option<bool>) -> StyledStr {
        let mut styled = StyledStr::new();
        // Write the name such --long or -l
        if let Some(l) = self.get_long() {
            styled.literal("--");
            styled.literal(l);
        } else if let Some(s) = self.get_short() {
            styled.literal("-");
            styled.literal(s);
        }
        styled.extend(self.stylize_arg_suffix(required).into_iter());
        styled
    }

    pub(crate) fn stylize_arg_suffix(&self, required: Option<bool>) -> StyledStr {
        let mut styled = StyledStr::new();

        let mut need_closing_bracket = false;
        if self.is_takes_value_set() && !self.is_positional() {
            let is_optional_val = self.get_min_vals() == 0;
            if self.is_require_equals_set() {
                if is_optional_val {
                    need_closing_bracket = true;
                    styled.placeholder("[=");
                } else {
                    styled.literal("=");
                }
            } else if is_optional_val {
                need_closing_bracket = true;
                styled.placeholder(" [");
            } else {
                styled.placeholder(" ");
            }
        }
        if self.is_takes_value_set() || self.is_positional() {
            let required = required.unwrap_or_else(|| self.is_required_set());
            let arg_val = self.render_arg_val(required);
            styled.placeholder(arg_val);
        } else if matches!(*self.get_action(), ArgAction::Count) {
            styled.placeholder("...");
        }
        if need_closing_bracket {
            styled.placeholder("]");
        }

        styled
    }

    /// Write the values such as <name1> <name2>
    fn render_arg_val(&self, required: bool) -> String {
        let mut rendered = String::new();

        let num_vals = self.get_num_args().unwrap_or_else(|| 1.into());

        let mut val_names = if self.val_names.is_empty() {
            vec![self.id.as_internal_str().to_owned()]
        } else {
            self.val_names.clone()
        };
        if val_names.len() == 1 {
            let min = num_vals.min_values().max(1);
            let val_name = val_names.pop().unwrap();
            val_names = vec![val_name; min];
        }

        debug_assert!(self.is_takes_value_set());
        for (n, val_name) in val_names.iter().enumerate() {
            let arg_name = if self.is_positional() && (num_vals.min_values() == 0 || !required) {
                format!("[{}]", val_name)
            } else {
                format!("<{}>", val_name)
            };

            if n != 0 {
                rendered.push(' ');
            }
            rendered.push_str(&arg_name);
        }

        let mut extra_values = false;
        extra_values |= val_names.len() < num_vals.max_values();
        if self.is_positional() && matches!(*self.get_action(), ArgAction::Append) {
            extra_values = true;
        }
        if extra_values {
            rendered.push_str("...");
        }

        rendered
    }

    /// Either multiple values or occurrences
    pub(crate) fn is_multiple(&self) -> bool {
        self.is_multiple_values_set() || matches!(*self.get_action(), ArgAction::Append)
    }

    #[cfg(feature = "help")]
    pub(crate) fn get_display_order(&self) -> usize {
        self.disp_ord.unwrap_or(999)
    }
}

impl From<&'_ Arg> for Arg {
    fn from(a: &Arg) -> Self {
        a.clone()
    }
}

impl PartialEq for Arg {
    fn eq(&self, other: &Arg) -> bool {
        self.get_id() == other.get_id()
    }
}

impl PartialOrd for Arg {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Arg {
    fn cmp(&self, other: &Arg) -> Ordering {
        self.get_id().cmp(other.get_id())
    }

src/output/help_template.rs (line 976)

fn option_sort_key(arg: &Arg) -> (usize, String) {
    // Formatting key like this to ensure that:
    // 1. Argument has long flags are printed just after short flags.
    // 2. For two args both have short flags like `-c` and `-C`, the
    //    `-C` arg is printed just after the `-c` arg
    // 3. For args without short or long flag, print them at last(sorted
    //    by arg name).
    // Example order: -a, -b, -B, -s, --select-file, --select-folder, -x

    let key = if let Some(x) = arg.get_short() {
        let mut s = x.to_ascii_lowercase().to_string();
        s.push(if x.is_ascii_lowercase() { '0' } else { '1' });
        s
    } else if let Some(x) = arg.get_long() {
        x.to_string()
    } else {
        let mut s = '{'.to_string();
        s.push_str(arg.get_id().as_str());
        s
    };
    (arg.get_display_order(), key)
}

src/output/usage.rs (line 173)

    fn needs_options_tag(&self) -> bool {
        debug!("Usage::needs_options_tag");
        'outer: for f in self.cmd.get_non_positionals() {
            debug!("Usage::needs_options_tag:iter: f={}", f.get_id());

            // Don't print `[OPTIONS]` just for help or version
            if f.get_long() == Some("help") || f.get_long() == Some("version") {
                debug!("Usage::needs_options_tag:iter Option is built-in");
                continue;
            }

            if f.is_hide_set() {
                debug!("Usage::needs_options_tag:iter Option is hidden");
                continue;
            }
            if f.is_required_set() {
                debug!("Usage::needs_options_tag:iter Option is required");
                continue;
            }
            for grp_s in self.cmd.groups_for_arg(f.get_id()) {
                debug!("Usage::needs_options_tag:iter:iter: grp_s={:?}", grp_s);
                if self.cmd.get_groups().any(|g| g.id == grp_s && g.required) {
                    debug!("Usage::needs_options_tag:iter:iter: Group is required");
                    continue 'outer;
                }
            }

            debug!("Usage::needs_options_tag:iter: [OPTIONS] required");
            return true;
        }

        debug!("Usage::needs_options_tag: [OPTIONS] not required");
        false
    }

    // Returns the required args in usage string form by fully unrolling all groups
    pub(crate) fn write_args(&self, incls: &[Id], force_optional: bool, styled: &mut StyledStr) {
        for required in self.get_args(incls, force_optional) {
            styled.none(" ");
            styled.extend(required.into_iter());
        }
    }

    pub(crate) fn get_args(&self, incls: &[Id], force_optional: bool) -> Vec<StyledStr> {
        debug!("Usage::get_args: incls={:?}", incls,);

        let required_owned;
        let required = if let Some(required) = self.required {
            required
        } else {
            required_owned = self.cmd.required_graph();
            &required_owned
        };

        let mut unrolled_reqs = Vec::new();
        for a in required.iter() {
            let is_relevant = |(val, req_arg): &(ArgPredicate, Id)| -> Option<Id> {
                let required = match val {
                    ArgPredicate::Equals(_) => false,
                    ArgPredicate::IsPresent => true,
                };
                required.then(|| req_arg.clone())
            };

            for aa in self.cmd.unroll_arg_requires(is_relevant, a) {
                // if we don't check for duplicates here this causes duplicate error messages
                // see https://github.com/clap-rs/clap/issues/2770
                unrolled_reqs.push(aa);
            }
            // always include the required arg itself. it will not be enumerated
            // by unroll_requirements_for_arg.
            unrolled_reqs.push(a.clone());
        }
        debug!("Usage::get_args: unrolled_reqs={:?}", unrolled_reqs);

        let mut required_groups_members = FlatSet::new();
        let mut required_groups = FlatSet::new();
        for req in unrolled_reqs.iter().chain(incls.iter()) {
            if self.cmd.find_group(req).is_some() {
                let group_members = self.cmd.unroll_args_in_group(req);
                let elem = self.cmd.format_group(req);
                required_groups.insert(elem);
                required_groups_members.extend(group_members);
            } else {
                debug_assert!(self.cmd.find(req).is_some());
            }
        }

        let mut required_opts = FlatSet::new();
        let mut required_positionals = Vec::new();
        for req in unrolled_reqs.iter().chain(incls.iter()) {
            if let Some(arg) = self.cmd.find(req) {
                if required_groups_members.contains(arg.get_id()) {
                    continue;
                }

                let stylized = arg.stylized(Some(!force_optional));
                if let Some(index) = arg.get_index() {
                    let new_len = index + 1;
                    if required_positionals.len() < new_len {
                        required_positionals.resize(new_len, None);
                    }
                    required_positionals[index] = Some(stylized);
                } else {
                    required_opts.insert(stylized);
                }
            } else {
                debug_assert!(self.cmd.find_group(req).is_some());
            }
        }

        for pos in self.cmd.get_positionals() {
            if pos.is_hide_set() {
                continue;
            }
            if required_groups_members.contains(pos.get_id()) {
                continue;
            }

            let index = pos.get_index().unwrap();
            let new_len = index + 1;
            if required_positionals.len() < new_len {
                required_positionals.resize(new_len, None);
            }
            if required_positionals[index].is_some() {
                if pos.is_last_set() {
                    let styled = required_positionals[index].take().unwrap();
                    let mut new = StyledStr::new();
                    new.literal("-- ");
                    new.extend(styled.into_iter());
                    required_positionals[index] = Some(new);
                }
            } else {
                let mut styled;
                if pos.is_last_set() {
                    styled = StyledStr::new();
                    styled.literal("[-- ");
                    styled.extend(pos.stylized(Some(true)).into_iter());
                    styled.literal("]");
                } else {
                    styled = pos.stylized(Some(false));
                }
                required_positionals[index] = Some(styled);
            }
            if pos.is_last_set() && force_optional {
                required_positionals[index] = None;
            }
        }

        let mut ret_val = Vec::new();
        if !force_optional {
            ret_val.extend(required_opts);
            ret_val.extend(required_groups);
        }
        for pos in required_positionals.into_iter().flatten() {
            ret_val.push(pos);
        }

        debug!("Usage::get_args: ret_val={:?}", ret_val);
        ret_val
    }

    pub(crate) fn get_required_usage_from(
        &self,
        incls: &[Id],
        matcher: Option<&ArgMatcher>,
        incl_last: bool,
    ) -> Vec<StyledStr> {
        debug!(
            "Usage::get_required_usage_from: incls={:?}, matcher={:?}, incl_last={:?}",
            incls,
            matcher.is_some(),
            incl_last
        );

        let required_owned;
        let required = if let Some(required) = self.required {
            required
        } else {
            required_owned = self.cmd.required_graph();
            &required_owned
        };

        let mut unrolled_reqs = Vec::new();
        for a in required.iter() {
            let is_relevant = |(val, req_arg): &(ArgPredicate, Id)| -> Option<Id> {
                let required = match val {
                    ArgPredicate::Equals(_) => {
                        if let Some(matcher) = matcher {
                            matcher.check_explicit(a, val)
                        } else {
                            false
                        }
                    }
                    ArgPredicate::IsPresent => true,
                };
                required.then(|| req_arg.clone())
            };

            for aa in self.cmd.unroll_arg_requires(is_relevant, a) {
                // if we don't check for duplicates here this causes duplicate error messages
                // see https://github.com/clap-rs/clap/issues/2770
                unrolled_reqs.push(aa);
            }
            // always include the required arg itself. it will not be enumerated
            // by unroll_requirements_for_arg.
            unrolled_reqs.push(a.clone());
        }
        debug!(
            "Usage::get_required_usage_from: unrolled_reqs={:?}",
            unrolled_reqs
        );

        let mut required_groups_members = FlatSet::new();
        let mut required_groups = FlatSet::new();
        for req in unrolled_reqs.iter().chain(incls.iter()) {
            if self.cmd.find_group(req).is_some() {
                let group_members = self.cmd.unroll_args_in_group(req);
                let is_present = matcher
                    .map(|m| {
                        group_members
                            .iter()
                            .any(|arg| m.check_explicit(arg, &ArgPredicate::IsPresent))
                    })
                    .unwrap_or(false);
                debug!(
                    "Usage::get_required_usage_from:iter:{:?} group is_present={}",
                    req, is_present
                );
                if is_present {
                    continue;
                }

                let elem = self.cmd.format_group(req);
                required_groups.insert(elem);
                required_groups_members.extend(group_members);
            } else {
                debug_assert!(self.cmd.find(req).is_some());
            }
        }

        let mut required_opts = FlatSet::new();
        let mut required_positionals = Vec::new();
        for req in unrolled_reqs.iter().chain(incls.iter()) {
            if let Some(arg) = self.cmd.find(req) {
                if required_groups_members.contains(arg.get_id()) {
                    continue;
                }

                let is_present = matcher
                    .map(|m| m.check_explicit(req, &ArgPredicate::IsPresent))
                    .unwrap_or(false);
                debug!(
                    "Usage::get_required_usage_from:iter:{:?} arg is_present={}",
                    req, is_present
                );
                if is_present {
                    continue;
                }

                let stylized = arg.stylized(Some(true));
                if let Some(index) = arg.get_index() {
                    if !arg.is_last_set() || incl_last {
                        let new_len = index + 1;
                        if required_positionals.len() < new_len {
                            required_positionals.resize(new_len, None);
                        }
                        required_positionals[index] = Some(stylized);
                    }
                } else {
                    required_opts.insert(stylized);
                }
            } else {
                debug_assert!(self.cmd.find_group(req).is_some());
            }
        }

        let mut ret_val = Vec::new();
        ret_val.extend(required_opts);
        ret_val.extend(required_groups);
        for pos in required_positionals.into_iter().flatten() {
            ret_val.push(pos);
        }

        debug!("Usage::get_required_usage_from: ret_val={:?}", ret_val);
        ret_val
    }

src/parser/validator.rs (line 37)

    pub(crate) fn validate(
        &mut self,
        parse_state: ParseState,
        matcher: &mut ArgMatcher,
    ) -> ClapResult<()> {
        debug!("Validator::validate");
        let mut conflicts = Conflicts::new();
        let has_subcmd = matcher.subcommand_name().is_some();

        if let ParseState::Opt(a) = parse_state {
            debug!("Validator::validate: needs_val_of={:?}", a);

            let o = &self.cmd[&a];
            let should_err = if let Some(v) = matcher.args.get(o.get_id()) {
                v.all_val_groups_empty() && o.get_min_vals() != 0
            } else {
                true
            };
            if should_err {
                return Err(Error::empty_value(
                    self.cmd,
                    &get_possible_values_cli(o)
                        .iter()
                        .filter(|pv| !pv.is_hide_set())
                        .map(|n| n.get_name().to_owned())
                        .collect::<Vec<_>>(),
                    o.to_string(),
                ));
            }
        }

        if !has_subcmd && self.cmd.is_arg_required_else_help_set() {
            let num_user_values = matcher
                .arg_ids()
                .filter(|arg_id| matcher.check_explicit(arg_id, &ArgPredicate::IsPresent))
                .count();
            if num_user_values == 0 {
                let message = self.cmd.write_help_err(false);
                return Err(Error::display_help_error(self.cmd, message));
            }
        }
        if !has_subcmd && self.cmd.is_subcommand_required_set() {
            let bn = self
                .cmd
                .get_bin_name()
                .unwrap_or_else(|| self.cmd.get_name());
            return Err(Error::missing_subcommand(
                self.cmd,
                bn.to_string(),
                self.cmd
                    .all_subcommand_names()
                    .map(|s| s.to_owned())
                    .collect::<Vec<_>>(),
                Usage::new(self.cmd)
                    .required(&self.required)
                    .create_usage_with_title(&[]),
            ));
        }

        ok!(self.validate_conflicts(matcher, &mut conflicts));
        if !(self.cmd.is_subcommand_negates_reqs_set() && has_subcmd) {
            ok!(self.validate_required(matcher, &mut conflicts));
        }

        Ok(())
    }

    fn validate_conflicts(
        &mut self,
        matcher: &ArgMatcher,
        conflicts: &mut Conflicts,
    ) -> ClapResult<()> {
        debug!("Validator::validate_conflicts");

        ok!(self.validate_exclusive(matcher));

        for arg_id in matcher
            .arg_ids()
            .filter(|arg_id| matcher.check_explicit(arg_id, &ArgPredicate::IsPresent))
            .filter(|arg_id| self.cmd.find(arg_id).is_some())
        {
            debug!("Validator::validate_conflicts::iter: id={:?}", arg_id);
            let conflicts = conflicts.gather_conflicts(self.cmd, matcher, arg_id);
            ok!(self.build_conflict_err(arg_id, &conflicts, matcher));
        }

        Ok(())
    }

    fn validate_exclusive(&self, matcher: &ArgMatcher) -> ClapResult<()> {
        debug!("Validator::validate_exclusive");
        let args_count = matcher
            .arg_ids()
            .filter(|arg_id| {
                matcher.check_explicit(arg_id, &crate::builder::ArgPredicate::IsPresent)
                    // Avoid including our own groups by checking none of them.  If a group is present, the
                    // args for the group will be.
                    && self.cmd.find(arg_id).is_some()
            })
            .count();
        if args_count <= 1 {
            // Nothing present to conflict with
            return Ok(());
        }

        matcher
            .arg_ids()
            .filter(|arg_id| {
                matcher.check_explicit(arg_id, &crate::builder::ArgPredicate::IsPresent)
            })
            .filter_map(|name| {
                debug!("Validator::validate_exclusive:iter:{:?}", name);
                self.cmd
                    .find(name)
                    // Find `arg`s which are exclusive but also appear with other args.
                    .filter(|&arg| arg.is_exclusive_set() && args_count > 1)
            })
            // Throw an error for the first conflict found.
            .try_for_each(|arg| {
                Err(Error::argument_conflict(
                    self.cmd,
                    arg.to_string(),
                    Vec::new(),
                    Usage::new(self.cmd)
                        .required(&self.required)
                        .create_usage_with_title(&[]),
                ))
            })
    }

    fn build_conflict_err(
        &self,
        name: &Id,
        conflict_ids: &[Id],
        matcher: &ArgMatcher,
    ) -> ClapResult<()> {
        if conflict_ids.is_empty() {
            return Ok(());
        }

        debug!("Validator::build_conflict_err: name={:?}", name);
        let mut seen = FlatSet::new();
        let conflicts = conflict_ids
            .iter()
            .flat_map(|c_id| {
                if self.cmd.find_group(c_id).is_some() {
                    self.cmd.unroll_args_in_group(c_id)
                } else {
                    vec![c_id.clone()]
                }
            })
            .filter_map(|c_id| {
                seen.insert(c_id.clone()).then(|| {
                    let c_arg = self.cmd.find(&c_id).expect(INTERNAL_ERROR_MSG);
                    c_arg.to_string()
                })
            })
            .collect();

        let former_arg = self.cmd.find(name).expect(INTERNAL_ERROR_MSG);
        let usg = self.build_conflict_err_usage(matcher, conflict_ids);
        Err(Error::argument_conflict(
            self.cmd,
            former_arg.to_string(),
            conflicts,
            usg,
        ))
    }

    fn build_conflict_err_usage(
        &self,
        matcher: &ArgMatcher,
        conflicting_keys: &[Id],
    ) -> Option<StyledStr> {
        let used_filtered: Vec<Id> = matcher
            .arg_ids()
            .filter(|arg_id| matcher.check_explicit(arg_id, &ArgPredicate::IsPresent))
            .filter(|n| {
                // Filter out the args we don't want to specify.
                self.cmd.find(n).map_or(false, |a| !a.is_hide_set())
            })
            .filter(|key| !conflicting_keys.contains(key))
            .cloned()
            .collect();
        let required: Vec<Id> = used_filtered
            .iter()
            .filter_map(|key| self.cmd.find(key))
            .flat_map(|arg| arg.requires.iter().map(|item| &item.1))
            .filter(|key| !used_filtered.contains(key) && !conflicting_keys.contains(key))
            .chain(used_filtered.iter())
            .cloned()
            .collect();
        Usage::new(self.cmd)
            .required(&self.required)
            .create_usage_with_title(&required)
    }

    fn gather_requires(&mut self, matcher: &ArgMatcher) {
        debug!("Validator::gather_requires");
        for name in matcher
            .arg_ids()
            .filter(|arg_id| matcher.check_explicit(arg_id, &ArgPredicate::IsPresent))
        {
            debug!("Validator::gather_requires:iter:{:?}", name);
            if let Some(arg) = self.cmd.find(name) {
                let is_relevant = |(val, req_arg): &(ArgPredicate, Id)| -> Option<Id> {
                    let required = matcher.check_explicit(arg.get_id(), val);
                    required.then(|| req_arg.clone())
                };

                for req in self.cmd.unroll_arg_requires(is_relevant, arg.get_id()) {
                    self.required.insert(req);
                }
            } else if let Some(g) = self.cmd.find_group(name) {
                debug!("Validator::gather_requires:iter:{:?}:group", name);
                for r in &g.requires {
                    self.required.insert(r.clone());
                }
            }
        }
    }

    fn validate_required(
        &mut self,
        matcher: &ArgMatcher,
        conflicts: &mut Conflicts,
    ) -> ClapResult<()> {
        debug!("Validator::validate_required: required={:?}", self.required);
        self.gather_requires(matcher);

        let mut missing_required = Vec::new();
        let mut highest_index = 0;

        let is_exclusive_present = matcher
            .arg_ids()
            .filter(|arg_id| matcher.check_explicit(arg_id, &ArgPredicate::IsPresent))
            .any(|id| {
                self.cmd
                    .find(id)
                    .map(|arg| arg.is_exclusive_set())
                    .unwrap_or_default()
            });
        debug!(
            "Validator::validate_required: is_exclusive_present={}",
            is_exclusive_present
        );

        for arg_or_group in self
            .required
            .iter()
            .filter(|r| !matcher.check_explicit(r, &ArgPredicate::IsPresent))
        {
            debug!("Validator::validate_required:iter:aog={:?}", arg_or_group);
            if let Some(arg) = self.cmd.find(arg_or_group) {
                debug!("Validator::validate_required:iter: This is an arg");
                if !is_exclusive_present && !self.is_missing_required_ok(arg, matcher, conflicts) {
                    debug!(
                        "Validator::validate_required:iter: Missing {:?}",
                        arg.get_id()
                    );
                    missing_required.push(arg.get_id().clone());
                    if !arg.is_last_set() {
                        highest_index = highest_index.max(arg.get_index().unwrap_or(0));
                    }
                }
            } else if let Some(group) = self.cmd.find_group(arg_or_group) {
                debug!("Validator::validate_required:iter: This is a group");
                if !self
                    .cmd
                    .unroll_args_in_group(&group.id)
                    .iter()
                    .any(|a| matcher.check_explicit(a, &ArgPredicate::IsPresent))
                {
                    debug!(
                        "Validator::validate_required:iter: Missing {:?}",
                        group.get_id()
                    );
                    missing_required.push(group.get_id().clone());
                }
            }
        }

        // Validate the conditionally required args
        for a in self
            .cmd
            .get_arguments()
            .filter(|a| !matcher.check_explicit(a.get_id(), &ArgPredicate::IsPresent))
        {
            let mut required = false;

            for (other, val) in &a.r_ifs {
                if matcher.check_explicit(other, &ArgPredicate::Equals(val.into())) {
                    debug!(
                        "Validator::validate_required:iter: Missing {:?}",
                        a.get_id()
                    );
                    required = true;
                }
            }

            let match_all = a.r_ifs_all.iter().all(|(other, val)| {
                matcher.check_explicit(other, &ArgPredicate::Equals(val.into()))
            });
            if match_all && !a.r_ifs_all.is_empty() {
                debug!(
                    "Validator::validate_required:iter: Missing {:?}",
                    a.get_id()
                );
                required = true;
            }

            if (!a.r_unless.is_empty() || !a.r_unless_all.is_empty())
                && self.fails_arg_required_unless(a, matcher)
            {
                debug!(
                    "Validator::validate_required:iter: Missing {:?}",
                    a.get_id()
                );
                required = true;
            }

            if required {
                missing_required.push(a.get_id().clone());
                if !a.is_last_set() {
                    highest_index = highest_index.max(a.get_index().unwrap_or(0));
                }
            }
        }

        // For display purposes, include all of the preceding positional arguments
        if !self.cmd.is_allow_missing_positional_set() {
            for pos in self
                .cmd
                .get_positionals()
                .filter(|a| !matcher.check_explicit(a.get_id(), &ArgPredicate::IsPresent))
            {
                if pos.get_index() < Some(highest_index) {
                    debug!(
                        "Validator::validate_required:iter: Missing {:?}",
                        pos.get_id()
                    );
                    missing_required.push(pos.get_id().clone());
                }
            }
        }

        if !missing_required.is_empty() {
            ok!(self.missing_required_error(matcher, missing_required));
        }

        Ok(())
    }

    fn is_missing_required_ok(
        &self,
        a: &Arg,
        matcher: &ArgMatcher,
        conflicts: &mut Conflicts,
    ) -> bool {
        debug!("Validator::is_missing_required_ok: {}", a.get_id());
        let conflicts = conflicts.gather_conflicts(self.cmd, matcher, a.get_id());
        !conflicts.is_empty()
    }

Additional examples can be found in:

• src/builder/debug_asserts.rs
• src/parser/parser.rs

pub fn get_help(&self) -> Option<&StyledStr>

Get the help specified for this argument, if any

Examples found in repository

src/output/help_template.rs (line 471)

    fn write_arg(&mut self, arg: &Arg, next_line_help: bool, longest: usize) {
        let spec_vals = &self.spec_vals(arg);

        self.none(TAB);
        self.short(arg);
        self.long(arg);
        self.writer.extend(arg.stylize_arg_suffix(None).into_iter());
        self.align_to_about(arg, next_line_help, longest);

        let about = if self.use_long {
            arg.get_long_help()
                .or_else(|| arg.get_help())
                .unwrap_or_default()
        } else {
            arg.get_help()
                .or_else(|| arg.get_long_help())
                .unwrap_or_default()
        };

        self.help(Some(arg), about, spec_vals, next_line_help, longest);
    }

    /// Writes argument's short command to the wrapped stream.
    fn short(&mut self, arg: &Arg) {
        debug!("HelpTemplate::short");

        if let Some(s) = arg.get_short() {
            self.literal(format!("-{}", s));
        } else if arg.get_long().is_some() {
            self.none("    ");
        }
    }

    /// Writes argument's long command to the wrapped stream.
    fn long(&mut self, arg: &Arg) {
        debug!("HelpTemplate::long");
        if let Some(long) = arg.get_long() {
            if arg.get_short().is_some() {
                self.none(", ");
            }
            self.literal(format!("--{}", long));
        }
    }

    /// Write alignment padding between arg's switches/values and its about message.
    fn align_to_about(&mut self, arg: &Arg, next_line_help: bool, longest: usize) {
        debug!(
            "HelpTemplate::align_to_about: arg={}, next_line_help={}, longest={}",
            arg.get_id(),
            next_line_help,
            longest
        );
        if self.use_long || next_line_help {
            // long help prints messages on the next line so it doesn't need to align text
            debug!("HelpTemplate::align_to_about: printing long help so skip alignment");
        } else if !arg.is_positional() {
            let self_len = display_width(&arg.to_string());
            // Since we're writing spaces from the tab point we first need to know if we
            // had a long and short, or just short
            let padding = if arg.get_long().is_some() {
                // Only account 4 after the val
                TAB_WIDTH
            } else {
                // Only account for ', --' + 4 after the val
                TAB_WIDTH + 4
            };
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=false arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        } else {
            let self_len = display_width(&arg.to_string());
            let padding = TAB_WIDTH;
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=true arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        }
    }

    /// Writes argument's help to the wrapped stream.
    fn help(
        &mut self,
        arg: Option<&Arg>,
        about: &StyledStr,
        spec_vals: &str,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::help");

        // Is help on next line, if so then indent
        if next_line_help {
            debug!("HelpTemplate::help: Next Line...{:?}", next_line_help);
            self.none("\n");
            self.none(TAB);
            self.none(NEXT_LINE_INDENT);
        }

        let spaces = if next_line_help {
            TAB.len() + NEXT_LINE_INDENT.len()
        } else if let Some(true) = arg.map(|a| a.is_positional()) {
            longest + TAB_WIDTH * 2
        } else {
            longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
        };
        let trailing_indent = spaces; // Don't indent any further than the first line is indented
        let trailing_indent = self.get_spaces(trailing_indent);

        let mut help = about.clone();
        replace_newline_var(&mut help);
        if !spec_vals.is_empty() {
            if !help.is_empty() {
                let sep = if self.use_long && arg.is_some() {
                    "\n\n"
                } else {
                    " "
                };
                help.none(sep);
            }
            help.none(spec_vals);
        }
        let avail_chars = self.term_w.saturating_sub(spaces);
        debug!(
            "HelpTemplate::help: help_width={}, spaces={}, avail={}",
            spaces,
            help.display_width(),
            avail_chars
        );
        help.wrap(avail_chars);
        help.indent("", &trailing_indent);
        let help_is_empty = help.is_empty();
        self.writer.extend(help.into_iter());
        if let Some(arg) = arg {
            const DASH_SPACE: usize = "- ".len();
            const COLON_SPACE: usize = ": ".len();
            let possible_vals = arg.get_possible_values();
            if self.use_long
                && !arg.is_hide_possible_values_set()
                && possible_vals.iter().any(PossibleValue::should_show_help)
            {
                debug!(
                    "HelpTemplate::help: Found possible vals...{:?}",
                    possible_vals
                );
                if !help_is_empty {
                    self.none("\n\n");
                    self.spaces(spaces);
                }
                self.none("Possible values:");
                let longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_quoted_name().map(|name| display_width(&name)))
                    .max()
                    .expect("Only called with possible value");
                let help_longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_help().map(|h| h.display_width()))
                    .max()
                    .expect("Only called with possible value with help");
                // should new line
                let taken = longest + spaces + DASH_SPACE;

                let possible_value_new_line =
                    self.term_w >= taken && self.term_w < taken + COLON_SPACE + help_longest;

                let spaces = spaces + TAB_WIDTH - DASH_SPACE;
                let trailing_indent = if possible_value_new_line {
                    spaces + DASH_SPACE
                } else {
                    spaces + longest + DASH_SPACE + COLON_SPACE
                };
                let trailing_indent = self.get_spaces(trailing_indent);

                for pv in possible_vals.iter().filter(|pv| !pv.is_hide_set()) {
                    self.none("\n");
                    self.spaces(spaces);
                    self.none("- ");
                    self.literal(pv.get_name());
                    if let Some(help) = pv.get_help() {
                        debug!("HelpTemplate::help: Possible Value help");

                        if possible_value_new_line {
                            self.none(":\n");
                            self.spaces(trailing_indent.len());
                        } else {
                            self.none(": ");
                            // To align help messages
                            self.spaces(longest - display_width(pv.get_name()));
                        }

                        let avail_chars = if self.term_w > trailing_indent.len() {
                            self.term_w - trailing_indent.len()
                        } else {
                            usize::MAX
                        };

                        let mut help = help.clone();
                        replace_newline_var(&mut help);
                        help.wrap(avail_chars);
                        help.indent("", &trailing_indent);
                        self.writer.extend(help.into_iter());
                    }
                }
            }
        }
    }

    /// Will use next line help on writing args.
    fn will_args_wrap(&self, args: &[&Arg], longest: usize) -> bool {
        args.iter()
            .filter(|arg| should_show_arg(self.use_long, arg))
            .any(|arg| {
                let spec_vals = &self.spec_vals(arg);
                self.arg_next_line_help(arg, spec_vals, longest)
            })
    }

    fn arg_next_line_help(&self, arg: &Arg, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help || arg.is_next_line_help_set() || self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = arg.get_help().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = if arg.is_positional() {
                longest + TAB_WIDTH * 2
            } else {
                longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
            };
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

src/builder/command.rs (line 4132)

    pub(crate) fn _panic_on_missing_help(&self, help_required_globally: bool) {
        if self.is_set(AppSettings::HelpExpected) || help_required_globally {
            let args_missing_help: Vec<Id> = self
                .args
                .args()
                .filter(|arg| arg.get_help().is_none() && arg.get_long_help().is_none())
                .map(|arg| arg.get_id().clone())
                .collect();

            debug_assert!(args_missing_help.is_empty(),
                    "Command::help_expected is enabled for the Command {}, but at least one of its arguments does not have either `help` or `long_help` set. List of such arguments: {}",
                    self.name,
                    args_missing_help.join(", ")
                );
        }

        for sub_app in &self.subcommands {
            sub_app._panic_on_missing_help(help_required_globally);
        }
    }

pub fn get_long_help(&self) -> Option<&StyledStr>

Get the long help specified for this argument, if any

Examples

let arg = Arg::new("foo").long_help("long help");
assert_eq!(Some("long help".to_owned()), arg.get_long_help().map(|s| s.to_string()));

Examples found in repository

src/output/help_template.rs (line 470)

    fn write_arg(&mut self, arg: &Arg, next_line_help: bool, longest: usize) {
        let spec_vals = &self.spec_vals(arg);

        self.none(TAB);
        self.short(arg);
        self.long(arg);
        self.writer.extend(arg.stylize_arg_suffix(None).into_iter());
        self.align_to_about(arg, next_line_help, longest);

        let about = if self.use_long {
            arg.get_long_help()
                .or_else(|| arg.get_help())
                .unwrap_or_default()
        } else {
            arg.get_help()
                .or_else(|| arg.get_long_help())
                .unwrap_or_default()
        };

        self.help(Some(arg), about, spec_vals, next_line_help, longest);
    }

src/builder/command.rs (line 4132)

    pub(crate) fn _panic_on_missing_help(&self, help_required_globally: bool) {
        if self.is_set(AppSettings::HelpExpected) || help_required_globally {
            let args_missing_help: Vec<Id> = self
                .args
                .args()
                .filter(|arg| arg.get_help().is_none() && arg.get_long_help().is_none())
                .map(|arg| arg.get_id().clone())
                .collect();

            debug_assert!(args_missing_help.is_empty(),
                    "Command::help_expected is enabled for the Command {}, but at least one of its arguments does not have either `help` or `long_help` set. List of such arguments: {}",
                    self.name,
                    args_missing_help.join(", ")
                );
        }

        for sub_app in &self.subcommands {
            sub_app._panic_on_missing_help(help_required_globally);
        }
    }

    #[cfg(debug_assertions)]
    pub(crate) fn two_args_of<F>(&self, condition: F) -> Option<(&Arg, &Arg)>
    where
        F: Fn(&Arg) -> bool,
    {
        two_elements_of(self.args.args().filter(|a: &&Arg| condition(a)))
    }

    // just in case
    #[allow(unused)]
    fn two_groups_of<F>(&self, condition: F) -> Option<(&ArgGroup, &ArgGroup)>
    where
        F: Fn(&ArgGroup) -> bool,
    {
        two_elements_of(self.groups.iter().filter(|a| condition(a)))
    }

    /// Propagate global args
    pub(crate) fn _propagate_global_args(&mut self) {
        debug!("Command::_propagate_global_args:{}", self.name);

        let autogenerated_help_subcommand = !self.is_disable_help_subcommand_set();

        for sc in &mut self.subcommands {
            if sc.get_name() == "help" && autogenerated_help_subcommand {
                // Avoid propagating args to the autogenerated help subtrees used in completion.
                // This prevents args from showing up during help completions like
                // `myapp help subcmd <TAB>`, which should only suggest subcommands and not args,
                // while still allowing args to show up properly on the generated help message.
                continue;
            }

            for a in self.args.args().filter(|a| a.is_global_set()) {
                if sc.find(&a.id).is_some() {
                    debug!(
                        "Command::_propagate skipping {:?} to {}, already exists",
                        a.id,
                        sc.get_name(),
                    );
                    continue;
                }

                debug!(
                    "Command::_propagate pushing {:?} to {}",
                    a.id,
                    sc.get_name(),
                );
                sc.args.push(a.clone());
            }
        }
    }

    /// Propagate settings
    pub(crate) fn _propagate(&mut self) {
        debug!("Command::_propagate:{}", self.name);
        let mut subcommands = std::mem::take(&mut self.subcommands);
        for sc in &mut subcommands {
            self._propagate_subcommand(sc);
        }
        self.subcommands = subcommands;
    }

    fn _propagate_subcommand(&self, sc: &mut Self) {
        // We have to create a new scope in order to tell rustc the borrow of `sc` is
        // done and to recursively call this method
        {
            if self.settings.is_set(AppSettings::PropagateVersion) {
                if let Some(version) = self.version.as_ref() {
                    sc.version.get_or_insert_with(|| version.clone());
                }
                if let Some(long_version) = self.long_version.as_ref() {
                    sc.long_version.get_or_insert_with(|| long_version.clone());
                }
            }

            sc.settings = sc.settings | self.g_settings;
            sc.g_settings = sc.g_settings | self.g_settings;
            sc.term_w = self.term_w;
            sc.max_w = self.max_w;
        }
    }

    pub(crate) fn _check_help_and_version(&mut self, expand_help_tree: bool) {
        debug!(
            "Command::_check_help_and_version:{} expand_help_tree={}",
            self.name, expand_help_tree
        );

        self.long_help_exists = self.long_help_exists_();

        if !self.is_disable_help_flag_set() {
            debug!("Command::_check_help_and_version: Building default --help");
            let mut arg = Arg::new(Id::HELP)
                .short('h')
                .long("help")
                .action(ArgAction::Help);
            if self.long_help_exists {
                arg = arg
                    .help("Print help information (use `--help` for more detail)")
                    .long_help("Print help information (use `-h` for a summary)");
            } else {
                arg = arg.help("Print help information");
            }
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }
        if !self.is_disable_version_flag_set() {
            debug!("Command::_check_help_and_version: Building default --version");
            let arg = Arg::new(Id::VERSION)
                .short('V')
                .long("version")
                .action(ArgAction::Version)
                .help("Print version information");
            // Avoiding `arg_internal` to not be sensitive to `next_help_heading` /
            // `next_display_order`
            self.args.push(arg);
        }

        if !self.is_set(AppSettings::DisableHelpSubcommand) {
            debug!("Command::_check_help_and_version: Building help subcommand");
            let help_about = "Print this message or the help of the given subcommand(s)";

            let mut help_subcmd = if expand_help_tree {
                // Slow code path to recursively clone all other subcommand subtrees under help
                let help_subcmd = Command::new("help")
                    .about(help_about)
                    .global_setting(AppSettings::DisableHelpSubcommand)
                    .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));

                let mut help_help_subcmd = Command::new("help").about(help_about);
                help_help_subcmd.version = None;
                help_help_subcmd.long_version = None;
                help_help_subcmd = help_help_subcmd
                    .setting(AppSettings::DisableHelpFlag)
                    .setting(AppSettings::DisableVersionFlag);

                help_subcmd.subcommand(help_help_subcmd)
            } else {
                Command::new("help").about(help_about).arg(
                    Arg::new("subcommand")
                        .action(ArgAction::Append)
                        .num_args(..)
                        .value_name("COMMAND")
                        .help("Print help for the subcommand(s)"),
                )
            };
            self._propagate_subcommand(&mut help_subcmd);

            // The parser acts like this is set, so let's set it so we don't falsely
            // advertise it to the user
            help_subcmd.version = None;
            help_subcmd.long_version = None;
            help_subcmd = help_subcmd
                .setting(AppSettings::DisableHelpFlag)
                .setting(AppSettings::DisableVersionFlag)
                .unset_global_setting(AppSettings::PropagateVersion);

            self.subcommands.push(help_subcmd);
        }
    }

    fn _copy_subtree_for_help(&self) -> Command {
        let mut cmd = Command::new(self.name.clone())
            .hide(self.is_hide_set())
            .global_setting(AppSettings::DisableHelpFlag)
            .global_setting(AppSettings::DisableVersionFlag)
            .subcommands(self.get_subcommands().map(Command::_copy_subtree_for_help));
        if self.get_about().is_some() {
            cmd = cmd.about(self.get_about().unwrap().clone());
        }
        cmd
    }

    pub(crate) fn _render_version(&self, use_long: bool) -> String {
        debug!("Command::_render_version");

        let ver = if use_long {
            self.long_version
                .as_deref()
                .or(self.version.as_deref())
                .unwrap_or_default()
        } else {
            self.version
                .as_deref()
                .or(self.long_version.as_deref())
                .unwrap_or_default()
        };
        let display_name = self.get_display_name().unwrap_or_else(|| self.get_name());
        format!("{} {}\n", display_name, ver)
    }

    pub(crate) fn format_group(&self, g: &Id) -> StyledStr {
        let g_string = self
            .unroll_args_in_group(g)
            .iter()
            .filter_map(|x| self.find(x))
            .map(|x| {
                if x.is_positional() {
                    // Print val_name for positional arguments. e.g. <file_name>
                    x.name_no_brackets()
                } else {
                    // Print usage string for flags arguments, e.g. <--help>
                    x.to_string()
                }
            })
            .collect::<Vec<_>>()
            .join("|");
        let mut styled = StyledStr::new();
        styled.none("<");
        styled.none(g_string);
        styled.none(">");
        styled
    }
}

/// A workaround:
/// <https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999>
pub(crate) trait Captures<'a> {}
impl<'a, T> Captures<'a> for T {}

// Internal Query Methods
impl Command {
    /// Iterate through the *flags* & *options* arguments.
    #[cfg(any(feature = "usage", feature = "help"))]
    pub(crate) fn get_non_positionals(&self) -> impl Iterator<Item = &Arg> {
        self.get_arguments().filter(|a| !a.is_positional())
    }

    pub(crate) fn find(&self, arg_id: &Id) -> Option<&Arg> {
        self.args.args().find(|a| a.get_id() == arg_id)
    }

    #[inline]
    pub(crate) fn contains_short(&self, s: char) -> bool {
        debug_assert!(
            self.is_set(AppSettings::Built),
            "If Command::_build hasn't been called, manually search through Arg shorts"
        );

        self.args.contains(s)
    }

    #[inline]
    pub(crate) fn set(&mut self, s: AppSettings) {
        self.settings.set(s)
    }

    #[inline]
    pub(crate) fn has_positionals(&self) -> bool {
        self.get_positionals().next().is_some()
    }

    #[cfg(any(feature = "usage", feature = "help"))]
    pub(crate) fn has_visible_subcommands(&self) -> bool {
        self.subcommands
            .iter()
            .any(|sc| sc.name != "help" && !sc.is_set(AppSettings::Hidden))
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this subcommand or is one of its aliases.
    #[inline]
    pub(crate) fn aliases_to(&self, name: impl AsRef<std::ffi::OsStr>) -> bool {
        let name = name.as_ref();
        self.get_name() == name || self.get_all_aliases().any(|alias| alias == name)
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this short flag subcommand or is one of its short flag aliases.
    #[inline]
    pub(crate) fn short_flag_aliases_to(&self, flag: char) -> bool {
        Some(flag) == self.short_flag
            || self.get_all_short_flag_aliases().any(|alias| flag == alias)
    }

    /// Check if this subcommand can be referred to as `name`. In other words,
    /// check if `name` is the name of this long flag subcommand or is one of its long flag aliases.
    #[inline]
    pub(crate) fn long_flag_aliases_to(&self, flag: &str) -> bool {
        match self.long_flag.as_ref() {
            Some(long_flag) => {
                long_flag == flag || self.get_all_long_flag_aliases().any(|alias| alias == flag)
            }
            None => self.get_all_long_flag_aliases().any(|alias| alias == flag),
        }
    }

    #[cfg(debug_assertions)]
    pub(crate) fn id_exists(&self, id: &Id) -> bool {
        self.args.args().any(|x| x.get_id() == id) || self.groups.iter().any(|x| x.id == *id)
    }

    /// Iterate through the groups this arg is member of.
    pub(crate) fn groups_for_arg<'a>(&'a self, arg: &Id) -> impl Iterator<Item = Id> + 'a {
        debug!("Command::groups_for_arg: id={:?}", arg);
        let arg = arg.clone();
        self.groups
            .iter()
            .filter(move |grp| grp.args.iter().any(|a| a == &arg))
            .map(|grp| grp.id.clone())
    }

    pub(crate) fn find_group(&self, group_id: &Id) -> Option<&ArgGroup> {
        self.groups.iter().find(|g| g.id == *group_id)
    }

    /// Iterate through all the names of all subcommands (not recursively), including aliases.
    /// Used for suggestions.
    pub(crate) fn all_subcommand_names(&self) -> impl Iterator<Item = &str> + Captures {
        self.get_subcommands().flat_map(|sc| {
            let name = sc.get_name();
            let aliases = sc.get_all_aliases();
            std::iter::once(name).chain(aliases)
        })
    }

    pub(crate) fn required_graph(&self) -> ChildGraph<Id> {
        let mut reqs = ChildGraph::with_capacity(5);
        for a in self.args.args().filter(|a| a.is_required_set()) {
            reqs.insert(a.get_id().clone());
        }
        for group in &self.groups {
            if group.required {
                let idx = reqs.insert(group.id.clone());
                for a in &group.requires {
                    reqs.insert_child(idx, a.clone());
                }
            }
        }

        reqs
    }

    pub(crate) fn unroll_args_in_group(&self, group: &Id) -> Vec<Id> {
        debug!("Command::unroll_args_in_group: group={:?}", group);
        let mut g_vec = vec![group];
        let mut args = vec![];

        while let Some(g) = g_vec.pop() {
            for n in self
                .groups
                .iter()
                .find(|grp| grp.id == *g)
                .expect(INTERNAL_ERROR_MSG)
                .args
                .iter()
            {
                debug!("Command::unroll_args_in_group:iter: entity={:?}", n);
                if !args.contains(n) {
                    if self.find(n).is_some() {
                        debug!("Command::unroll_args_in_group:iter: this is an arg");
                        args.push(n.clone())
                    } else {
                        debug!("Command::unroll_args_in_group:iter: this is a group");
                        g_vec.push(n);
                    }
                }
            }
        }

        args
    }

    pub(crate) fn unroll_arg_requires<F>(&self, func: F, arg: &Id) -> Vec<Id>
    where
        F: Fn(&(ArgPredicate, Id)) -> Option<Id>,
    {
        let mut processed = vec![];
        let mut r_vec = vec![arg];
        let mut args = vec![];

        while let Some(a) = r_vec.pop() {
            if processed.contains(&a) {
                continue;
            }

            processed.push(a);

            if let Some(arg) = self.find(a) {
                for r in arg.requires.iter().filter_map(&func) {
                    if let Some(req) = self.find(&r) {
                        if !req.requires.is_empty() {
                            r_vec.push(req.get_id())
                        }
                    }
                    args.push(r);
                }
            }
        }

        args
    }

    /// Find a flag subcommand name by short flag or an alias
    pub(crate) fn find_short_subcmd(&self, c: char) -> Option<&str> {
        self.get_subcommands()
            .find(|sc| sc.short_flag_aliases_to(c))
            .map(|sc| sc.get_name())
    }

    /// Find a flag subcommand name by long flag or an alias
    pub(crate) fn find_long_subcmd(&self, long: &str) -> Option<&str> {
        self.get_subcommands()
            .find(|sc| sc.long_flag_aliases_to(long))
            .map(|sc| sc.get_name())
    }

    #[cfg(feature = "help")]
    pub(crate) fn get_display_order(&self) -> usize {
        self.disp_ord.unwrap_or(999)
    }

    pub(crate) fn write_help_err(&self, mut use_long: bool) -> StyledStr {
        debug!(
            "Command::write_help_err: {}, use_long={:?}",
            self.get_display_name().unwrap_or_else(|| self.get_name()),
            use_long && self.long_help_exists(),
        );

        use_long = use_long && self.long_help_exists();
        let usage = Usage::new(self);

        let mut styled = StyledStr::new();
        write_help(&mut styled, self, &usage, use_long);

        styled
    }

    pub(crate) fn write_version_err(&self, use_long: bool) -> StyledStr {
        let msg = self._render_version(use_long);
        let mut styled = StyledStr::new();
        styled.none(msg);
        styled
    }

    pub(crate) fn long_help_exists(&self) -> bool {
        debug!("Command::long_help_exists: {}", self.long_help_exists);
        self.long_help_exists
    }

    fn long_help_exists_(&self) -> bool {
        debug!("Command::long_help_exists");
        // In this case, both must be checked. This allows the retention of
        // original formatting, but also ensures that the actual -h or --help
        // specified by the user is sent through. If hide_short_help is not included,
        // then items specified with hidden_short_help will also be hidden.
        let should_long = |v: &Arg| {
            v.get_long_help().is_some()
                || v.is_hide_long_help_set()
                || v.is_hide_short_help_set()
                || v.get_possible_values()
                    .iter()
                    .any(PossibleValue::should_show_help)
        };

        // Subcommands aren't checked because we prefer short help for them, deferring to
        // `cmd subcmd --help` for more.
        self.get_long_about().is_some()
            || self.get_before_long_help().is_some()
            || self.get_after_long_help().is_some()
            || self.get_arguments().any(should_long)
    }

pub fn get_help_heading(&self) -> Option<&str>

Get the help heading specified for this argument, if any

Examples found in repository

src/output/help_template.rs (line 340)

    pub(crate) fn write_all_args(&mut self) {
        debug!("HelpTemplate::write_all_args");
        let pos = self
            .cmd
            .get_positionals()
            .filter(|a| a.get_help_heading().is_none())
            .filter(|arg| should_show_arg(self.use_long, arg))
            .collect::<Vec<_>>();
        let non_pos = self
            .cmd
            .get_non_positionals()
            .filter(|a| a.get_help_heading().is_none())
            .filter(|arg| should_show_arg(self.use_long, arg))
            .collect::<Vec<_>>();
        let subcmds = self.cmd.has_visible_subcommands();

        let custom_headings = self
            .cmd
            .get_arguments()
            .filter_map(|arg| arg.get_help_heading())
            .collect::<FlatSet<_>>();

        let mut first = true;

        if subcmds {
            if !first {
                self.none("\n\n");
            }
            first = false;
            let default_help_heading = Str::from("Commands");
            self.header(
                self.cmd
                    .get_subcommand_help_heading()
                    .unwrap_or(&default_help_heading),
            );
            self.header(":\n");

            self.write_subcommands(self.cmd);
        }

        if !pos.is_empty() {
            if !first {
                self.none("\n\n");
            }
            first = false;
            // Write positional args if any
            self.header("Arguments:\n");
            self.write_args(&pos, "Arguments", positional_sort_key);
        }

        if !non_pos.is_empty() {
            if !first {
                self.none("\n\n");
            }
            first = false;
            self.header("Options:\n");
            self.write_args(&non_pos, "Options", option_sort_key);
        }
        if !custom_headings.is_empty() {
            for heading in custom_headings {
                let args = self
                    .cmd
                    .get_arguments()
                    .filter(|a| {
                        if let Some(help_heading) = a.get_help_heading() {
                            return help_heading == heading;
                        }
                        false
                    })
                    .filter(|arg| should_show_arg(self.use_long, arg))
                    .collect::<Vec<_>>();

                if !args.is_empty() {
                    if !first {
                        self.none("\n\n");
                    }
                    first = false;
                    self.header(format!("{}:\n", heading));
                    self.write_args(&args, heading, option_sort_key);
                }
            }
        }
    }

pub fn get_short(&self) -> Option<char>

Get the short option name for this argument, if any

Examples found in repository

src/builder/arg.rs (line 3924)

    pub fn is_positional(&self) -> bool {
        self.get_long().is_none() && self.get_short().is_none()
    }

    /// Reports whether [`Arg::required`] is set
    pub fn is_required_set(&self) -> bool {
        self.is_set(ArgSettings::Required)
    }

    pub(crate) fn is_multiple_values_set(&self) -> bool {
        self.get_num_args().unwrap_or_default().is_multiple()
    }

    pub(crate) fn is_takes_value_set(&self) -> bool {
        self.get_action().takes_values()
    }

    /// Report whether [`Arg::allow_hyphen_values`] is set
    pub fn is_allow_hyphen_values_set(&self) -> bool {
        self.is_set(ArgSettings::AllowHyphenValues)
    }

    /// Report whether [`Arg::allow_negative_numbers`] is set
    pub fn is_allow_negative_numbers_set(&self) -> bool {
        self.is_set(ArgSettings::AllowNegativeNumbers)
    }

    /// Behavior when parsing the argument
    pub fn get_action(&self) -> &super::ArgAction {
        const DEFAULT: super::ArgAction = super::ArgAction::Set;
        self.action.as_ref().unwrap_or(&DEFAULT)
    }

    /// Configured parser for argument values
    ///
    /// # Example
    ///
    /// ```rust
    /// let cmd = clap::Command::new("raw")
    ///     .arg(
    ///         clap::Arg::new("port")
    ///             .value_parser(clap::value_parser!(usize))
    ///     );
    /// let value_parser = cmd.get_arguments()
    ///     .find(|a| a.get_id() == "port").unwrap()
    ///     .get_value_parser();
    /// println!("{:?}", value_parser);
    /// ```
    pub fn get_value_parser(&self) -> &super::ValueParser {
        if let Some(value_parser) = self.value_parser.as_ref() {
            value_parser
        } else {
            static DEFAULT: super::ValueParser = super::ValueParser::string();
            &DEFAULT
        }
    }

    /// Report whether [`Arg::global`] is set
    pub fn is_global_set(&self) -> bool {
        self.is_set(ArgSettings::Global)
    }

    /// Report whether [`Arg::next_line_help`] is set
    pub fn is_next_line_help_set(&self) -> bool {
        self.is_set(ArgSettings::NextLineHelp)
    }

    /// Report whether [`Arg::hide`] is set
    pub fn is_hide_set(&self) -> bool {
        self.is_set(ArgSettings::Hidden)
    }

    /// Report whether [`Arg::hide_default_value`] is set
    pub fn is_hide_default_value_set(&self) -> bool {
        self.is_set(ArgSettings::HideDefaultValue)
    }

    /// Report whether [`Arg::hide_possible_values`] is set
    pub fn is_hide_possible_values_set(&self) -> bool {
        self.is_set(ArgSettings::HidePossibleValues)
    }

    /// Report whether [`Arg::hide_env`] is set
    #[cfg(feature = "env")]
    pub fn is_hide_env_set(&self) -> bool {
        self.is_set(ArgSettings::HideEnv)
    }

    /// Report whether [`Arg::hide_env_values`] is set
    #[cfg(feature = "env")]
    pub fn is_hide_env_values_set(&self) -> bool {
        self.is_set(ArgSettings::HideEnvValues)
    }

    /// Report whether [`Arg::hide_short_help`] is set
    pub fn is_hide_short_help_set(&self) -> bool {
        self.is_set(ArgSettings::HiddenShortHelp)
    }

    /// Report whether [`Arg::hide_long_help`] is set
    pub fn is_hide_long_help_set(&self) -> bool {
        self.is_set(ArgSettings::HiddenLongHelp)
    }

    /// Report whether [`Arg::require_equals`] is set
    pub fn is_require_equals_set(&self) -> bool {
        self.is_set(ArgSettings::RequireEquals)
    }

    /// Reports whether [`Arg::exclusive`] is set
    pub fn is_exclusive_set(&self) -> bool {
        self.is_set(ArgSettings::Exclusive)
    }

    /// Report whether [`Arg::trailing_var_arg`] is set
    pub fn is_trailing_var_arg_set(&self) -> bool {
        self.is_set(ArgSettings::TrailingVarArg)
    }

    /// Reports whether [`Arg::last`] is set
    pub fn is_last_set(&self) -> bool {
        self.is_set(ArgSettings::Last)
    }

    /// Reports whether [`Arg::ignore_case`] is set
    pub fn is_ignore_case_set(&self) -> bool {
        self.is_set(ArgSettings::IgnoreCase)
    }
}

/// # Internally used only
impl Arg {
    pub(crate) fn _build(&mut self) {
        if self.action.is_none() {
            if self.num_vals == Some(ValueRange::EMPTY) {
                let action = super::ArgAction::SetTrue;
                self.action = Some(action);
            } else {
                let action =
                    if self.is_positional() && self.num_vals.unwrap_or_default().is_unbounded() {
                        // Allow collecting arguments interleaved with flags
                        //
                        // Bounded values are probably a group and the user should explicitly opt-in to
                        // Append
                        super::ArgAction::Append
                    } else {
                        super::ArgAction::Set
                    };
                self.action = Some(action);
            }
        }
        if let Some(action) = self.action.as_ref() {
            if let Some(default_value) = action.default_value() {
                if self.default_vals.is_empty() {
                    self.default_vals = vec![default_value.into()];
                }
            }
            if let Some(default_value) = action.default_missing_value() {
                if self.default_missing_vals.is_empty() {
                    self.default_missing_vals = vec![default_value.into()];
                }
            }
        }

        if self.value_parser.is_none() {
            if let Some(default) = self.action.as_ref().and_then(|a| a.default_value_parser()) {
                self.value_parser = Some(default);
            } else {
                self.value_parser = Some(super::ValueParser::string());
            }
        }

        let val_names_len = self.val_names.len();
        if val_names_len > 1 {
            self.num_vals.get_or_insert(val_names_len.into());
        } else {
            let nargs = if self.get_action().takes_values() {
                ValueRange::SINGLE
            } else {
                ValueRange::EMPTY
            };
            self.num_vals.get_or_insert(nargs);
        }
    }

    // Used for positionals when printing
    pub(crate) fn name_no_brackets(&self) -> String {
        debug!("Arg::name_no_brackets:{}", self.get_id());
        let delim = " ";
        if !self.val_names.is_empty() {
            debug!("Arg::name_no_brackets: val_names={:#?}", self.val_names);

            if self.val_names.len() > 1 {
                self.val_names
                    .iter()
                    .map(|n| format!("<{}>", n))
                    .collect::<Vec<_>>()
                    .join(delim)
            } else {
                self.val_names
                    .first()
                    .expect(INTERNAL_ERROR_MSG)
                    .as_str()
                    .to_owned()
            }
        } else {
            debug!("Arg::name_no_brackets: just name");
            self.get_id().as_str().to_owned()
        }
    }

    pub(crate) fn stylized(&self, required: Option<bool>) -> StyledStr {
        let mut styled = StyledStr::new();
        // Write the name such --long or -l
        if let Some(l) = self.get_long() {
            styled.literal("--");
            styled.literal(l);
        } else if let Some(s) = self.get_short() {
            styled.literal("-");
            styled.literal(s);
        }
        styled.extend(self.stylize_arg_suffix(required).into_iter());
        styled
    }

src/output/help_template.rs (line 486)

    fn short(&mut self, arg: &Arg) {
        debug!("HelpTemplate::short");

        if let Some(s) = arg.get_short() {
            self.literal(format!("-{}", s));
        } else if arg.get_long().is_some() {
            self.none("    ");
        }
    }

    /// Writes argument's long command to the wrapped stream.
    fn long(&mut self, arg: &Arg) {
        debug!("HelpTemplate::long");
        if let Some(long) = arg.get_long() {
            if arg.get_short().is_some() {
                self.none(", ");
            }
            self.literal(format!("--{}", long));
        }
    }

    /// Write alignment padding between arg's switches/values and its about message.
    fn align_to_about(&mut self, arg: &Arg, next_line_help: bool, longest: usize) {
        debug!(
            "HelpTemplate::align_to_about: arg={}, next_line_help={}, longest={}",
            arg.get_id(),
            next_line_help,
            longest
        );
        if self.use_long || next_line_help {
            // long help prints messages on the next line so it doesn't need to align text
            debug!("HelpTemplate::align_to_about: printing long help so skip alignment");
        } else if !arg.is_positional() {
            let self_len = display_width(&arg.to_string());
            // Since we're writing spaces from the tab point we first need to know if we
            // had a long and short, or just short
            let padding = if arg.get_long().is_some() {
                // Only account 4 after the val
                TAB_WIDTH
            } else {
                // Only account for ', --' + 4 after the val
                TAB_WIDTH + 4
            };
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=false arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        } else {
            let self_len = display_width(&arg.to_string());
            let padding = TAB_WIDTH;
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=true arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        }
    }

    /// Writes argument's help to the wrapped stream.
    fn help(
        &mut self,
        arg: Option<&Arg>,
        about: &StyledStr,
        spec_vals: &str,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::help");

        // Is help on next line, if so then indent
        if next_line_help {
            debug!("HelpTemplate::help: Next Line...{:?}", next_line_help);
            self.none("\n");
            self.none(TAB);
            self.none(NEXT_LINE_INDENT);
        }

        let spaces = if next_line_help {
            TAB.len() + NEXT_LINE_INDENT.len()
        } else if let Some(true) = arg.map(|a| a.is_positional()) {
            longest + TAB_WIDTH * 2
        } else {
            longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
        };
        let trailing_indent = spaces; // Don't indent any further than the first line is indented
        let trailing_indent = self.get_spaces(trailing_indent);

        let mut help = about.clone();
        replace_newline_var(&mut help);
        if !spec_vals.is_empty() {
            if !help.is_empty() {
                let sep = if self.use_long && arg.is_some() {
                    "\n\n"
                } else {
                    " "
                };
                help.none(sep);
            }
            help.none(spec_vals);
        }
        let avail_chars = self.term_w.saturating_sub(spaces);
        debug!(
            "HelpTemplate::help: help_width={}, spaces={}, avail={}",
            spaces,
            help.display_width(),
            avail_chars
        );
        help.wrap(avail_chars);
        help.indent("", &trailing_indent);
        let help_is_empty = help.is_empty();
        self.writer.extend(help.into_iter());
        if let Some(arg) = arg {
            const DASH_SPACE: usize = "- ".len();
            const COLON_SPACE: usize = ": ".len();
            let possible_vals = arg.get_possible_values();
            if self.use_long
                && !arg.is_hide_possible_values_set()
                && possible_vals.iter().any(PossibleValue::should_show_help)
            {
                debug!(
                    "HelpTemplate::help: Found possible vals...{:?}",
                    possible_vals
                );
                if !help_is_empty {
                    self.none("\n\n");
                    self.spaces(spaces);
                }
                self.none("Possible values:");
                let longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_quoted_name().map(|name| display_width(&name)))
                    .max()
                    .expect("Only called with possible value");
                let help_longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_help().map(|h| h.display_width()))
                    .max()
                    .expect("Only called with possible value with help");
                // should new line
                let taken = longest + spaces + DASH_SPACE;

                let possible_value_new_line =
                    self.term_w >= taken && self.term_w < taken + COLON_SPACE + help_longest;

                let spaces = spaces + TAB_WIDTH - DASH_SPACE;
                let trailing_indent = if possible_value_new_line {
                    spaces + DASH_SPACE
                } else {
                    spaces + longest + DASH_SPACE + COLON_SPACE
                };
                let trailing_indent = self.get_spaces(trailing_indent);

                for pv in possible_vals.iter().filter(|pv| !pv.is_hide_set()) {
                    self.none("\n");
                    self.spaces(spaces);
                    self.none("- ");
                    self.literal(pv.get_name());
                    if let Some(help) = pv.get_help() {
                        debug!("HelpTemplate::help: Possible Value help");

                        if possible_value_new_line {
                            self.none(":\n");
                            self.spaces(trailing_indent.len());
                        } else {
                            self.none(": ");
                            // To align help messages
                            self.spaces(longest - display_width(pv.get_name()));
                        }

                        let avail_chars = if self.term_w > trailing_indent.len() {
                            self.term_w - trailing_indent.len()
                        } else {
                            usize::MAX
                        };

                        let mut help = help.clone();
                        replace_newline_var(&mut help);
                        help.wrap(avail_chars);
                        help.indent("", &trailing_indent);
                        self.writer.extend(help.into_iter());
                    }
                }
            }
        }
    }

    /// Will use next line help on writing args.
    fn will_args_wrap(&self, args: &[&Arg], longest: usize) -> bool {
        args.iter()
            .filter(|arg| should_show_arg(self.use_long, arg))
            .any(|arg| {
                let spec_vals = &self.spec_vals(arg);
                self.arg_next_line_help(arg, spec_vals, longest)
            })
    }

    fn arg_next_line_help(&self, arg: &Arg, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help || arg.is_next_line_help_set() || self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = arg.get_help().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = if arg.is_positional() {
                longest + TAB_WIDTH * 2
            } else {
                longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
            };
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

    fn spec_vals(&self, a: &Arg) -> String {
        debug!("HelpTemplate::spec_vals: a={}", a);
        let mut spec_vals = Vec::new();
        #[cfg(feature = "env")]
        if let Some(ref env) = a.env {
            if !a.is_hide_env_set() {
                debug!(
                    "HelpTemplate::spec_vals: Found environment variable...[{:?}:{:?}]",
                    env.0, env.1
                );
                let env_val = if !a.is_hide_env_values_set() {
                    format!(
                        "={}",
                        env.1
                            .as_ref()
                            .map(|s| s.to_string_lossy())
                            .unwrap_or_default()
                    )
                } else {
                    Default::default()
                };
                let env_info = format!("[env: {}{}]", env.0.to_string_lossy(), env_val);
                spec_vals.push(env_info);
            }
        }
        if a.is_takes_value_set() && !a.is_hide_default_value_set() && !a.default_vals.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found default value...[{:?}]",
                a.default_vals
            );

            let pvs = a
                .default_vals
                .iter()
                .map(|pvs| pvs.to_string_lossy())
                .map(|pvs| {
                    if pvs.contains(char::is_whitespace) {
                        Cow::from(format!("{:?}", pvs))
                    } else {
                        pvs
                    }
                })
                .collect::<Vec<_>>()
                .join(" ");

            spec_vals.push(format!("[default: {}]", pvs));
        }

        let als = a
            .aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|als| als.0.as_str()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!("HelpTemplate::spec_vals: Found aliases...{:?}", a.aliases);
            spec_vals.push(format!("[aliases: {}]", als));
        }

        let als = a
            .short_aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|&als| als.0.to_string()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found short aliases...{:?}",
                a.short_aliases
            );
            spec_vals.push(format!("[short aliases: {}]", als));
        }

        let possible_vals = a.get_possible_values();
        if !(a.is_hide_possible_values_set()
            || possible_vals.is_empty()
            || self.use_long && possible_vals.iter().any(PossibleValue::should_show_help))
        {
            debug!(
                "HelpTemplate::spec_vals: Found possible vals...{:?}",
                possible_vals
            );

            let pvs = possible_vals
                .iter()
                .filter_map(PossibleValue::get_visible_quoted_name)
                .collect::<Vec<_>>()
                .join(", ");

            spec_vals.push(format!("[possible values: {}]", pvs));
        }
        let connector = if self.use_long { "\n" } else { " " };
        spec_vals.join(connector)
    }

    fn header<T: Into<String>>(&mut self, msg: T) {
        self.writer.header(msg);
    }

    fn literal<T: Into<String>>(&mut self, msg: T) {
        self.writer.literal(msg);
    }

    fn none<T: Into<String>>(&mut self, msg: T) {
        self.writer.none(msg);
    }

    fn get_spaces(&self, n: usize) -> String {
        " ".repeat(n)
    }

    fn spaces(&mut self, n: usize) {
        self.none(self.get_spaces(n));
    }
}

/// Subcommand handling
impl<'cmd, 'writer> HelpTemplate<'cmd, 'writer> {
    /// Writes help for subcommands of a Parser Object to the wrapped stream.
    fn write_subcommands(&mut self, cmd: &Command) {
        debug!("HelpTemplate::write_subcommands");
        // The shortest an arg can legally be is 2 (i.e. '-x')
        let mut longest = 2;
        let mut ord_v = Vec::new();
        for subcommand in cmd
            .get_subcommands()
            .filter(|subcommand| should_show_subcommand(subcommand))
        {
            let mut styled = StyledStr::new();
            styled.literal(subcommand.get_name());
            if let Some(short) = subcommand.get_short_flag() {
                styled.none(", ");
                styled.literal(format!("-{}", short));
            }
            if let Some(long) = subcommand.get_long_flag() {
                styled.none(", ");
                styled.literal(format!("--{}", long));
            }
            longest = longest.max(styled.display_width());
            ord_v.push((subcommand.get_display_order(), styled, subcommand));
        }
        ord_v.sort_by(|a, b| (a.0, &a.1).cmp(&(b.0, &b.1)));

        debug!("HelpTemplate::write_subcommands longest = {}", longest);

        let next_line_help = self.will_subcommands_wrap(cmd.get_subcommands(), longest);

        let mut first = true;
        for (_, sc_str, sc) in ord_v {
            if first {
                first = false;
            } else {
                self.none("\n");
            }
            self.write_subcommand(sc_str, sc, next_line_help, longest);
        }
    }

    /// Will use next line help on writing subcommands.
    fn will_subcommands_wrap<'a>(
        &self,
        subcommands: impl IntoIterator<Item = &'a Command>,
        longest: usize,
    ) -> bool {
        subcommands
            .into_iter()
            .filter(|&subcommand| should_show_subcommand(subcommand))
            .any(|subcommand| {
                let spec_vals = &self.sc_spec_vals(subcommand);
                self.subcommand_next_line_help(subcommand, spec_vals, longest)
            })
    }

    fn write_subcommand(
        &mut self,
        sc_str: StyledStr,
        cmd: &Command,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::write_subcommand");

        let spec_vals = &self.sc_spec_vals(cmd);

        let about = cmd
            .get_about()
            .or_else(|| cmd.get_long_about())
            .unwrap_or_default();

        self.subcmd(sc_str, next_line_help, longest);
        self.help(None, about, spec_vals, next_line_help, longest)
    }

    fn sc_spec_vals(&self, a: &Command) -> String {
        debug!("HelpTemplate::sc_spec_vals: a={}", a.get_name());
        let mut spec_vals = vec![];

        let mut short_als = a
            .get_visible_short_flag_aliases()
            .map(|a| format!("-{}", a))
            .collect::<Vec<_>>();
        let als = a.get_visible_aliases().map(|s| s.to_string());
        short_als.extend(als);
        let all_als = short_als.join(", ");
        if !all_als.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found aliases...{:?}",
                a.get_all_aliases().collect::<Vec<_>>()
            );
            debug!(
                "HelpTemplate::spec_vals: Found short flag aliases...{:?}",
                a.get_all_short_flag_aliases().collect::<Vec<_>>()
            );
            spec_vals.push(format!("[aliases: {}]", all_als));
        }

        spec_vals.join(" ")
    }

    fn subcommand_next_line_help(&self, cmd: &Command, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help | self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = cmd.get_about().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = longest + TAB_WIDTH * 2;
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

    /// Writes subcommand to the wrapped stream.
    fn subcmd(&mut self, sc_str: StyledStr, next_line_help: bool, longest: usize) {
        let width = sc_str.display_width();

        self.none(TAB);
        self.writer.extend(sc_str.into_iter());
        if !next_line_help {
            self.spaces(longest + TAB_WIDTH - width);
        }
    }
}

const NEXT_LINE_INDENT: &str = "        ";

type ArgSortKey = fn(arg: &Arg) -> (usize, String);

fn positional_sort_key(arg: &Arg) -> (usize, String) {
    (arg.get_index().unwrap_or(0), String::new())
}

fn option_sort_key(arg: &Arg) -> (usize, String) {
    // Formatting key like this to ensure that:
    // 1. Argument has long flags are printed just after short flags.
    // 2. For two args both have short flags like `-c` and `-C`, the
    //    `-C` arg is printed just after the `-c` arg
    // 3. For args without short or long flag, print them at last(sorted
    //    by arg name).
    // Example order: -a, -b, -B, -s, --select-file, --select-folder, -x

    let key = if let Some(x) = arg.get_short() {
        let mut s = x.to_ascii_lowercase().to_string();
        s.push(if x.is_ascii_lowercase() { '0' } else { '1' });
        s
    } else if let Some(x) = arg.get_long() {
        x.to_string()
    } else {
        let mut s = '{'.to_string();
        s.push_str(arg.get_id().as_str());
        s
    };
    (arg.get_display_order(), key)
}

pub(crate) fn dimensions() -> (Option<usize>, Option<usize>) {
    #[cfg(not(feature = "wrap_help"))]
    return (None, None);

    #[cfg(feature = "wrap_help")]
    terminal_size::terminal_size()
        .map(|(w, h)| (Some(w.0.into()), Some(h.0.into())))
        .unwrap_or_else(|| (parse_env("COLUMNS"), parse_env("LINES")))
}

#[cfg(feature = "wrap_help")]
fn parse_env(var: &str) -> Option<usize> {
    some!(some!(std::env::var_os(var)).to_str())
        .parse::<usize>()
        .ok()
}

fn should_show_arg(use_long: bool, arg: &Arg) -> bool {
    debug!(
        "should_show_arg: use_long={:?}, arg={}",
        use_long,
        arg.get_id()
    );
    if arg.is_hide_set() {
        return false;
    }
    (!arg.is_hide_long_help_set() && use_long)
        || (!arg.is_hide_short_help_set() && !use_long)
        || arg.is_next_line_help_set()
}

fn should_show_subcommand(subcommand: &Command) -> bool {
    !subcommand.is_hide_set()
}

fn replace_newline_var(styled: &mut StyledStr) {
    for (_, content) in styled.iter_mut() {
        *content = content.replace("{n}", "\n");
    }
}

fn longest_filter(arg: &Arg) -> bool {
    arg.is_takes_value_set() || arg.get_long().is_some() || arg.get_short().is_none()
}

src/builder/debug_asserts.rs (line 70)

pub(crate) fn assert_app(cmd: &Command) {
    debug!("Command::_debug_asserts");

    let mut short_flags = vec![];
    let mut long_flags = vec![];

    // Invalid version flag settings
    if cmd.get_version().is_none() && cmd.get_long_version().is_none() {
        // PropagateVersion is meaningless if there is no version
        assert!(
            !cmd.is_propagate_version_set(),
            "Command {}: No version information via Command::version or Command::long_version to propagate",
            cmd.get_name(),
        );

        // Used `Command::mut_arg("version", ..) but did not provide any version information to display
        let version_needed = cmd
            .get_arguments()
            .filter(|x| matches!(x.get_action(), ArgAction::Version))
            .map(|x| x.get_id())
            .collect::<Vec<_>>();

        assert_eq!(version_needed, Vec::<&str>::new(), "Command {}: `ArgAction::Version` used without providing Command::version or Command::long_version"
            ,cmd.get_name()
        );
    }

    for sc in cmd.get_subcommands() {
        if let Some(s) = sc.get_short_flag().as_ref() {
            short_flags.push(Flag::Command(format!("-{}", s), sc.get_name()));
        }

        for short_alias in sc.get_all_short_flag_aliases() {
            short_flags.push(Flag::Command(format!("-{}", short_alias), sc.get_name()));
        }

        if let Some(l) = sc.get_long_flag().as_ref() {
            assert!(!l.starts_with('-'), "Command {}: long_flag {:?} must not start with a `-`, that will be handled by the parser", sc.get_name(), l);
            long_flags.push(Flag::Command(format!("--{}", l), sc.get_name()));
        }

        for long_alias in sc.get_all_long_flag_aliases() {
            long_flags.push(Flag::Command(format!("--{}", long_alias), sc.get_name()));
        }
    }

    for arg in cmd.get_arguments() {
        assert_arg(arg);

        assert!(
            !cmd.is_multicall_set(),
            "Command {}: Arguments like {} cannot be set on a multicall command",
            cmd.get_name(),
            arg.get_id()
        );

        if let Some(s) = arg.get_short() {
            short_flags.push(Flag::Arg(format!("-{}", s), arg.get_id().as_str()));
        }

        for (short_alias, _) in &arg.short_aliases {
            short_flags.push(Flag::Arg(
                format!("-{}", short_alias),
                arg.get_id().as_str(),
            ));
        }

        if let Some(l) = arg.get_long() {
            assert!(!l.starts_with('-'), "Argument {}: long {:?} must not start with a `-`, that will be handled by the parser", arg.get_id(), l);
            long_flags.push(Flag::Arg(format!("--{}", l), arg.get_id().as_str()));
        }

        for (long_alias, _) in &arg.aliases {
            long_flags.push(Flag::Arg(
                format!("--{}", long_alias),
                arg.get_id().as_str(),
            ));
        }

        // Name conflicts
        if let Some((first, second)) = cmd.two_args_of(|x| x.get_id() == arg.get_id()) {
            panic!(
            "Command {}: Argument names must be unique, but '{}' is in use by more than one argument or group{}",
            cmd.get_name(),
            arg.get_id(),
            duplicate_tip(cmd, first, second),
        );
        }

        // Long conflicts
        if let Some(l) = arg.get_long() {
            if let Some((first, second)) = cmd.two_args_of(|x| x.get_long() == Some(l)) {
                panic!(
                    "Command {}: Long option names must be unique for each argument, \
                            but '--{}' is in use by both '{}' and '{}'{}",
                    cmd.get_name(),
                    l,
                    first.get_id(),
                    second.get_id(),
                    duplicate_tip(cmd, first, second)
                )
            }
        }

        // Short conflicts
        if let Some(s) = arg.get_short() {
            if let Some((first, second)) = cmd.two_args_of(|x| x.get_short() == Some(s)) {
                panic!(
                    "Command {}: Short option names must be unique for each argument, \
                            but '-{}' is in use by both '{}' and '{}'{}",
                    cmd.get_name(),
                    s,
                    first.get_id(),
                    second.get_id(),
                    duplicate_tip(cmd, first, second),
                )
            }
        }

        // Index conflicts
        if let Some(idx) = arg.index {
            if let Some((first, second)) =
                cmd.two_args_of(|x| x.is_positional() && x.get_index() == Some(idx))
            {
                panic!(
                    "Command {}: Argument '{}' has the same index as '{}' \
                    and they are both positional arguments\n\n\t \
                    Use `Arg::num_args(1..)` to allow one \
                    positional argument to take multiple values",
                    cmd.get_name(),
                    first.get_id(),
                    second.get_id()
                )
            }
        }

        // requires, r_if, r_unless
        for req in &arg.requires {
            assert!(
                cmd.id_exists(&req.1),
                "Command {}: Argument or group '{}' specified in 'requires*' for '{}' does not exist",
                cmd.get_name(),
                req.1,
                arg.get_id(),
            );
        }

        for req in &arg.r_ifs {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_if_eq*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(&req.0),
                "Command {}: Argument or group '{}' specified in 'required_if_eq*' for '{}' does not exist",
                    cmd.get_name(),
                req.0,
                arg.get_id()
            );
        }

        for req in &arg.r_ifs_all {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_if_eq_all`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(&req.0),
                "Command {}: Argument or group '{}' specified in 'required_if_eq_all' for '{}' does not exist",
                    cmd.get_name(),
                req.0,
                arg.get_id()
            );
        }

        for req in &arg.r_unless {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_unless*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'required_unless*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        for req in &arg.r_unless_all {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_unless*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'required_unless*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        // blacklist
        for req in &arg.blacklist {
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'conflicts_with*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        // overrides
        for req in &arg.overrides {
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'overrides_with*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        if arg.is_last_set() {
            assert!(
                arg.get_long().is_none(),
                "Command {}: Flags or Options cannot have last(true) set. '{}' has both a long and last(true) set.",
                    cmd.get_name(),
                arg.get_id()
            );
            assert!(
                arg.get_short().is_none(),
                "Command {}: Flags or Options cannot have last(true) set. '{}' has both a short and last(true) set.",
                    cmd.get_name(),
                arg.get_id()
            );
        }

        assert!(
            !(arg.is_required_set() && arg.is_global_set()),
            "Command {}: Global arguments cannot be required.\n\n\t'{}' is marked as both global and required",
                    cmd.get_name(),
            arg.get_id()
        );

        if arg.get_value_hint() == ValueHint::CommandWithArguments {
            assert!(
                arg.is_positional(),
                "Command {}: Argument '{}' has hint CommandWithArguments and must be positional.",
                cmd.get_name(),
                arg.get_id()
            );

            assert!(
                arg.is_trailing_var_arg_set() || arg.is_last_set(),
                "Command {}: Positional argument '{}' has hint CommandWithArguments, so Command must have `trailing_var_arg(true)` or `last(true)` set.",
                    cmd.get_name(),
                arg.get_id()
            );
        }
    }

    for group in cmd.get_groups() {
        let derive_hint = if cfg!(feature = "derive") {
            " (note: `Args` implicitly creates `ArgGroup`s; disable with `#[group(skip)]`"
        } else {
            ""
        };

        // Name conflicts
        assert!(
            cmd.get_groups().filter(|x| x.id == group.id).count() < 2,
            "Command {}: Argument group name must be unique\n\n\t'{}' is already in use{}",
            cmd.get_name(),
            group.get_id(),
            derive_hint
        );

        // Groups should not have naming conflicts with Args
        assert!(
            !cmd.get_arguments().any(|x| x.get_id() == group.get_id()),
            "Command {}: Argument group name '{}' must not conflict with argument name{}",
            cmd.get_name(),
            group.get_id(),
            derive_hint
        );

        for arg in &group.args {
            // Args listed inside groups should exist
            assert!(
                cmd.get_arguments().any(|x| x.get_id() == arg),
                "Command {}: Argument group '{}' contains non-existent argument '{}'",
                cmd.get_name(),
                group.get_id(),
                arg
            );
        }
    }

    // Conflicts between flags and subcommands

    long_flags.sort_unstable();
    short_flags.sort_unstable();

    detect_duplicate_flags(&long_flags, "long");
    detect_duplicate_flags(&short_flags, "short");

    let mut subs = FlatSet::new();
    for sc in cmd.get_subcommands() {
        assert!(
            subs.insert(sc.get_name()),
            "Command {}: command name `{}` is duplicated",
            cmd.get_name(),
            sc.get_name()
        );
        for alias in sc.get_all_aliases() {
            assert!(
                subs.insert(alias),
                "Command {}: command `{}` alias `{}` is duplicated",
                cmd.get_name(),
                sc.get_name(),
                alias
            );
        }
    }

    _verify_positionals(cmd);

    #[cfg(feature = "help")]
    if let Some(help_template) = cmd.get_help_template() {
        assert!(
            !help_template.to_string().contains("{flags}"),
            "Command {}: {}",
                    cmd.get_name(),
            "`{flags}` template variable was removed in clap3, they are now included in `{options}`",
        );
        assert!(
            !help_template.to_string().contains("{unified}"),
            "Command {}: {}",
            cmd.get_name(),
            "`{unified}` template variable was removed in clap3, use `{options}` instead"
        );
    }

    cmd._panic_on_missing_help(cmd.is_help_expected_set());
    assert_app_flags(cmd);
}

pub fn get_visible_short_aliases(&self) -> Option<Vec<char>>

Get visible short aliases for this argument, if any

Examples found in repository

src/builder/arg.rs (line 3771)

    pub fn get_short_and_visible_aliases(&self) -> Option<Vec<char>> {
        let mut shorts = match self.short {
            Some(short) => vec![short],
            None => return None,
        };
        if let Some(aliases) = self.get_visible_short_aliases() {
            shorts.extend(aliases);
        }
        Some(shorts)
    }

pub fn get_all_short_aliases(&self) -> Option<Vec<char>>

Get all short aliases for this argument, if any, both visible and hidden.

pub fn get_short_and_visible_aliases(&self) -> Option<Vec<char>>

Get the short option name and its visible aliases, if any

pub fn get_long(&self) -> Option<&str>

Get the long option name for this argument, if any

Examples found in repository

src/output/help_template.rs (line 488)

    fn short(&mut self, arg: &Arg) {
        debug!("HelpTemplate::short");

        if let Some(s) = arg.get_short() {
            self.literal(format!("-{}", s));
        } else if arg.get_long().is_some() {
            self.none("    ");
        }
    }

    /// Writes argument's long command to the wrapped stream.
    fn long(&mut self, arg: &Arg) {
        debug!("HelpTemplate::long");
        if let Some(long) = arg.get_long() {
            if arg.get_short().is_some() {
                self.none(", ");
            }
            self.literal(format!("--{}", long));
        }
    }

    /// Write alignment padding between arg's switches/values and its about message.
    fn align_to_about(&mut self, arg: &Arg, next_line_help: bool, longest: usize) {
        debug!(
            "HelpTemplate::align_to_about: arg={}, next_line_help={}, longest={}",
            arg.get_id(),
            next_line_help,
            longest
        );
        if self.use_long || next_line_help {
            // long help prints messages on the next line so it doesn't need to align text
            debug!("HelpTemplate::align_to_about: printing long help so skip alignment");
        } else if !arg.is_positional() {
            let self_len = display_width(&arg.to_string());
            // Since we're writing spaces from the tab point we first need to know if we
            // had a long and short, or just short
            let padding = if arg.get_long().is_some() {
                // Only account 4 after the val
                TAB_WIDTH
            } else {
                // Only account for ', --' + 4 after the val
                TAB_WIDTH + 4
            };
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=false arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        } else {
            let self_len = display_width(&arg.to_string());
            let padding = TAB_WIDTH;
            let spcs = longest + padding - self_len;
            debug!(
                "HelpTemplate::align_to_about: positional=true arg_len={}, spaces={}",
                self_len, spcs
            );

            self.spaces(spcs);
        }
    }

    /// Writes argument's help to the wrapped stream.
    fn help(
        &mut self,
        arg: Option<&Arg>,
        about: &StyledStr,
        spec_vals: &str,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::help");

        // Is help on next line, if so then indent
        if next_line_help {
            debug!("HelpTemplate::help: Next Line...{:?}", next_line_help);
            self.none("\n");
            self.none(TAB);
            self.none(NEXT_LINE_INDENT);
        }

        let spaces = if next_line_help {
            TAB.len() + NEXT_LINE_INDENT.len()
        } else if let Some(true) = arg.map(|a| a.is_positional()) {
            longest + TAB_WIDTH * 2
        } else {
            longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
        };
        let trailing_indent = spaces; // Don't indent any further than the first line is indented
        let trailing_indent = self.get_spaces(trailing_indent);

        let mut help = about.clone();
        replace_newline_var(&mut help);
        if !spec_vals.is_empty() {
            if !help.is_empty() {
                let sep = if self.use_long && arg.is_some() {
                    "\n\n"
                } else {
                    " "
                };
                help.none(sep);
            }
            help.none(spec_vals);
        }
        let avail_chars = self.term_w.saturating_sub(spaces);
        debug!(
            "HelpTemplate::help: help_width={}, spaces={}, avail={}",
            spaces,
            help.display_width(),
            avail_chars
        );
        help.wrap(avail_chars);
        help.indent("", &trailing_indent);
        let help_is_empty = help.is_empty();
        self.writer.extend(help.into_iter());
        if let Some(arg) = arg {
            const DASH_SPACE: usize = "- ".len();
            const COLON_SPACE: usize = ": ".len();
            let possible_vals = arg.get_possible_values();
            if self.use_long
                && !arg.is_hide_possible_values_set()
                && possible_vals.iter().any(PossibleValue::should_show_help)
            {
                debug!(
                    "HelpTemplate::help: Found possible vals...{:?}",
                    possible_vals
                );
                if !help_is_empty {
                    self.none("\n\n");
                    self.spaces(spaces);
                }
                self.none("Possible values:");
                let longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_quoted_name().map(|name| display_width(&name)))
                    .max()
                    .expect("Only called with possible value");
                let help_longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_help().map(|h| h.display_width()))
                    .max()
                    .expect("Only called with possible value with help");
                // should new line
                let taken = longest + spaces + DASH_SPACE;

                let possible_value_new_line =
                    self.term_w >= taken && self.term_w < taken + COLON_SPACE + help_longest;

                let spaces = spaces + TAB_WIDTH - DASH_SPACE;
                let trailing_indent = if possible_value_new_line {
                    spaces + DASH_SPACE
                } else {
                    spaces + longest + DASH_SPACE + COLON_SPACE
                };
                let trailing_indent = self.get_spaces(trailing_indent);

                for pv in possible_vals.iter().filter(|pv| !pv.is_hide_set()) {
                    self.none("\n");
                    self.spaces(spaces);
                    self.none("- ");
                    self.literal(pv.get_name());
                    if let Some(help) = pv.get_help() {
                        debug!("HelpTemplate::help: Possible Value help");

                        if possible_value_new_line {
                            self.none(":\n");
                            self.spaces(trailing_indent.len());
                        } else {
                            self.none(": ");
                            // To align help messages
                            self.spaces(longest - display_width(pv.get_name()));
                        }

                        let avail_chars = if self.term_w > trailing_indent.len() {
                            self.term_w - trailing_indent.len()
                        } else {
                            usize::MAX
                        };

                        let mut help = help.clone();
                        replace_newline_var(&mut help);
                        help.wrap(avail_chars);
                        help.indent("", &trailing_indent);
                        self.writer.extend(help.into_iter());
                    }
                }
            }
        }
    }

    /// Will use next line help on writing args.
    fn will_args_wrap(&self, args: &[&Arg], longest: usize) -> bool {
        args.iter()
            .filter(|arg| should_show_arg(self.use_long, arg))
            .any(|arg| {
                let spec_vals = &self.spec_vals(arg);
                self.arg_next_line_help(arg, spec_vals, longest)
            })
    }

    fn arg_next_line_help(&self, arg: &Arg, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help || arg.is_next_line_help_set() || self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = arg.get_help().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = if arg.is_positional() {
                longest + TAB_WIDTH * 2
            } else {
                longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
            };
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

    fn spec_vals(&self, a: &Arg) -> String {
        debug!("HelpTemplate::spec_vals: a={}", a);
        let mut spec_vals = Vec::new();
        #[cfg(feature = "env")]
        if let Some(ref env) = a.env {
            if !a.is_hide_env_set() {
                debug!(
                    "HelpTemplate::spec_vals: Found environment variable...[{:?}:{:?}]",
                    env.0, env.1
                );
                let env_val = if !a.is_hide_env_values_set() {
                    format!(
                        "={}",
                        env.1
                            .as_ref()
                            .map(|s| s.to_string_lossy())
                            .unwrap_or_default()
                    )
                } else {
                    Default::default()
                };
                let env_info = format!("[env: {}{}]", env.0.to_string_lossy(), env_val);
                spec_vals.push(env_info);
            }
        }
        if a.is_takes_value_set() && !a.is_hide_default_value_set() && !a.default_vals.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found default value...[{:?}]",
                a.default_vals
            );

            let pvs = a
                .default_vals
                .iter()
                .map(|pvs| pvs.to_string_lossy())
                .map(|pvs| {
                    if pvs.contains(char::is_whitespace) {
                        Cow::from(format!("{:?}", pvs))
                    } else {
                        pvs
                    }
                })
                .collect::<Vec<_>>()
                .join(" ");

            spec_vals.push(format!("[default: {}]", pvs));
        }

        let als = a
            .aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|als| als.0.as_str()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!("HelpTemplate::spec_vals: Found aliases...{:?}", a.aliases);
            spec_vals.push(format!("[aliases: {}]", als));
        }

        let als = a
            .short_aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|&als| als.0.to_string()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found short aliases...{:?}",
                a.short_aliases
            );
            spec_vals.push(format!("[short aliases: {}]", als));
        }

        let possible_vals = a.get_possible_values();
        if !(a.is_hide_possible_values_set()
            || possible_vals.is_empty()
            || self.use_long && possible_vals.iter().any(PossibleValue::should_show_help))
        {
            debug!(
                "HelpTemplate::spec_vals: Found possible vals...{:?}",
                possible_vals
            );

            let pvs = possible_vals
                .iter()
                .filter_map(PossibleValue::get_visible_quoted_name)
                .collect::<Vec<_>>()
                .join(", ");

            spec_vals.push(format!("[possible values: {}]", pvs));
        }
        let connector = if self.use_long { "\n" } else { " " };
        spec_vals.join(connector)
    }

    fn header<T: Into<String>>(&mut self, msg: T) {
        self.writer.header(msg);
    }

    fn literal<T: Into<String>>(&mut self, msg: T) {
        self.writer.literal(msg);
    }

    fn none<T: Into<String>>(&mut self, msg: T) {
        self.writer.none(msg);
    }

    fn get_spaces(&self, n: usize) -> String {
        " ".repeat(n)
    }

    fn spaces(&mut self, n: usize) {
        self.none(self.get_spaces(n));
    }
}

/// Subcommand handling
impl<'cmd, 'writer> HelpTemplate<'cmd, 'writer> {
    /// Writes help for subcommands of a Parser Object to the wrapped stream.
    fn write_subcommands(&mut self, cmd: &Command) {
        debug!("HelpTemplate::write_subcommands");
        // The shortest an arg can legally be is 2 (i.e. '-x')
        let mut longest = 2;
        let mut ord_v = Vec::new();
        for subcommand in cmd
            .get_subcommands()
            .filter(|subcommand| should_show_subcommand(subcommand))
        {
            let mut styled = StyledStr::new();
            styled.literal(subcommand.get_name());
            if let Some(short) = subcommand.get_short_flag() {
                styled.none(", ");
                styled.literal(format!("-{}", short));
            }
            if let Some(long) = subcommand.get_long_flag() {
                styled.none(", ");
                styled.literal(format!("--{}", long));
            }
            longest = longest.max(styled.display_width());
            ord_v.push((subcommand.get_display_order(), styled, subcommand));
        }
        ord_v.sort_by(|a, b| (a.0, &a.1).cmp(&(b.0, &b.1)));

        debug!("HelpTemplate::write_subcommands longest = {}", longest);

        let next_line_help = self.will_subcommands_wrap(cmd.get_subcommands(), longest);

        let mut first = true;
        for (_, sc_str, sc) in ord_v {
            if first {
                first = false;
            } else {
                self.none("\n");
            }
            self.write_subcommand(sc_str, sc, next_line_help, longest);
        }
    }

    /// Will use next line help on writing subcommands.
    fn will_subcommands_wrap<'a>(
        &self,
        subcommands: impl IntoIterator<Item = &'a Command>,
        longest: usize,
    ) -> bool {
        subcommands
            .into_iter()
            .filter(|&subcommand| should_show_subcommand(subcommand))
            .any(|subcommand| {
                let spec_vals = &self.sc_spec_vals(subcommand);
                self.subcommand_next_line_help(subcommand, spec_vals, longest)
            })
    }

    fn write_subcommand(
        &mut self,
        sc_str: StyledStr,
        cmd: &Command,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::write_subcommand");

        let spec_vals = &self.sc_spec_vals(cmd);

        let about = cmd
            .get_about()
            .or_else(|| cmd.get_long_about())
            .unwrap_or_default();

        self.subcmd(sc_str, next_line_help, longest);
        self.help(None, about, spec_vals, next_line_help, longest)
    }

    fn sc_spec_vals(&self, a: &Command) -> String {
        debug!("HelpTemplate::sc_spec_vals: a={}", a.get_name());
        let mut spec_vals = vec![];

        let mut short_als = a
            .get_visible_short_flag_aliases()
            .map(|a| format!("-{}", a))
            .collect::<Vec<_>>();
        let als = a.get_visible_aliases().map(|s| s.to_string());
        short_als.extend(als);
        let all_als = short_als.join(", ");
        if !all_als.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found aliases...{:?}",
                a.get_all_aliases().collect::<Vec<_>>()
            );
            debug!(
                "HelpTemplate::spec_vals: Found short flag aliases...{:?}",
                a.get_all_short_flag_aliases().collect::<Vec<_>>()
            );
            spec_vals.push(format!("[aliases: {}]", all_als));
        }

        spec_vals.join(" ")
    }

    fn subcommand_next_line_help(&self, cmd: &Command, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help | self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = cmd.get_about().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = longest + TAB_WIDTH * 2;
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

    /// Writes subcommand to the wrapped stream.
    fn subcmd(&mut self, sc_str: StyledStr, next_line_help: bool, longest: usize) {
        let width = sc_str.display_width();

        self.none(TAB);
        self.writer.extend(sc_str.into_iter());
        if !next_line_help {
            self.spaces(longest + TAB_WIDTH - width);
        }
    }
}

const NEXT_LINE_INDENT: &str = "        ";

type ArgSortKey = fn(arg: &Arg) -> (usize, String);

fn positional_sort_key(arg: &Arg) -> (usize, String) {
    (arg.get_index().unwrap_or(0), String::new())
}

fn option_sort_key(arg: &Arg) -> (usize, String) {
    // Formatting key like this to ensure that:
    // 1. Argument has long flags are printed just after short flags.
    // 2. For two args both have short flags like `-c` and `-C`, the
    //    `-C` arg is printed just after the `-c` arg
    // 3. For args without short or long flag, print them at last(sorted
    //    by arg name).
    // Example order: -a, -b, -B, -s, --select-file, --select-folder, -x

    let key = if let Some(x) = arg.get_short() {
        let mut s = x.to_ascii_lowercase().to_string();
        s.push(if x.is_ascii_lowercase() { '0' } else { '1' });
        s
    } else if let Some(x) = arg.get_long() {
        x.to_string()
    } else {
        let mut s = '{'.to_string();
        s.push_str(arg.get_id().as_str());
        s
    };
    (arg.get_display_order(), key)
}

pub(crate) fn dimensions() -> (Option<usize>, Option<usize>) {
    #[cfg(not(feature = "wrap_help"))]
    return (None, None);

    #[cfg(feature = "wrap_help")]
    terminal_size::terminal_size()
        .map(|(w, h)| (Some(w.0.into()), Some(h.0.into())))
        .unwrap_or_else(|| (parse_env("COLUMNS"), parse_env("LINES")))
}

#[cfg(feature = "wrap_help")]
fn parse_env(var: &str) -> Option<usize> {
    some!(some!(std::env::var_os(var)).to_str())
        .parse::<usize>()
        .ok()
}

fn should_show_arg(use_long: bool, arg: &Arg) -> bool {
    debug!(
        "should_show_arg: use_long={:?}, arg={}",
        use_long,
        arg.get_id()
    );
    if arg.is_hide_set() {
        return false;
    }
    (!arg.is_hide_long_help_set() && use_long)
        || (!arg.is_hide_short_help_set() && !use_long)
        || arg.is_next_line_help_set()
}

fn should_show_subcommand(subcommand: &Command) -> bool {
    !subcommand.is_hide_set()
}

fn replace_newline_var(styled: &mut StyledStr) {
    for (_, content) in styled.iter_mut() {
        *content = content.replace("{n}", "\n");
    }
}

fn longest_filter(arg: &Arg) -> bool {
    arg.is_takes_value_set() || arg.get_long().is_some() || arg.get_short().is_none()
}

src/builder/arg.rs (line 3811)

    pub fn get_long_and_visible_aliases(&self) -> Option<Vec<&str>> {
        let mut longs = match self.get_long() {
            Some(long) => vec![long],
            None => return None,
        };
        if let Some(aliases) = self.get_visible_aliases() {
            longs.extend(aliases);
        }
        Some(longs)
    }

    /// Get the names of possible values for this argument. Only useful for user
    /// facing applications, such as building help messages or man files
    pub fn get_possible_values(&self) -> Vec<PossibleValue> {
        if !self.is_takes_value_set() {
            vec![]
        } else {
            self.get_value_parser()
                .possible_values()
                .map(|pvs| pvs.collect())
                .unwrap_or_default()
        }
    }

    /// Get the names of values for this argument.
    #[inline]
    pub fn get_value_names(&self) -> Option<&[Str]> {
        if self.val_names.is_empty() {
            None
        } else {
            Some(&self.val_names)
        }
    }

    /// Get the number of values for this argument.
    #[inline]
    pub fn get_num_args(&self) -> Option<ValueRange> {
        self.num_vals
    }

    #[inline]
    pub(crate) fn get_min_vals(&self) -> usize {
        self.get_num_args().expect(INTERNAL_ERROR_MSG).min_values()
    }

    /// Get the delimiter between multiple values
    #[inline]
    pub fn get_value_delimiter(&self) -> Option<char> {
        self.val_delim
    }

    /// Get the index of this argument, if any
    #[inline]
    pub fn get_index(&self) -> Option<usize> {
        self.index
    }

    /// Get the value hint of this argument
    pub fn get_value_hint(&self) -> ValueHint {
        self.value_hint.unwrap_or_else(|| {
            if self.is_takes_value_set() {
                let type_id = self.get_value_parser().type_id();
                if type_id == crate::parser::AnyValueId::of::<std::path::PathBuf>() {
                    ValueHint::AnyPath
                } else {
                    ValueHint::default()
                }
            } else {
                ValueHint::default()
            }
        })
    }

    /// Get the environment variable name specified for this argument, if any
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use std::ffi::OsStr;
    /// # use clap::Arg;
    /// let arg = Arg::new("foo").env("ENVIRONMENT");
    /// assert_eq!(arg.get_env(), Some(OsStr::new("ENVIRONMENT")));
    /// ```
    #[cfg(feature = "env")]
    pub fn get_env(&self) -> Option<&std::ffi::OsStr> {
        self.env.as_ref().map(|x| x.0.as_os_str())
    }

    /// Get the default values specified for this argument, if any
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use clap::Arg;
    /// let arg = Arg::new("foo").default_value("default value");
    /// assert_eq!(arg.get_default_values(), &["default value"]);
    /// ```
    pub fn get_default_values(&self) -> &[OsStr] {
        &self.default_vals
    }

    /// Checks whether this argument is a positional or not.
    ///
    /// # Examples
    ///
    /// ```
    /// # use clap::Arg;
    /// let arg = Arg::new("foo");
    /// assert_eq!(arg.is_positional(), true);
    ///
    /// let arg = Arg::new("foo").long("foo");
    /// assert_eq!(arg.is_positional(), false);
    /// ```
    pub fn is_positional(&self) -> bool {
        self.get_long().is_none() && self.get_short().is_none()
    }

    /// Reports whether [`Arg::required`] is set
    pub fn is_required_set(&self) -> bool {
        self.is_set(ArgSettings::Required)
    }

    pub(crate) fn is_multiple_values_set(&self) -> bool {
        self.get_num_args().unwrap_or_default().is_multiple()
    }

    pub(crate) fn is_takes_value_set(&self) -> bool {
        self.get_action().takes_values()
    }

    /// Report whether [`Arg::allow_hyphen_values`] is set
    pub fn is_allow_hyphen_values_set(&self) -> bool {
        self.is_set(ArgSettings::AllowHyphenValues)
    }

    /// Report whether [`Arg::allow_negative_numbers`] is set
    pub fn is_allow_negative_numbers_set(&self) -> bool {
        self.is_set(ArgSettings::AllowNegativeNumbers)
    }

    /// Behavior when parsing the argument
    pub fn get_action(&self) -> &super::ArgAction {
        const DEFAULT: super::ArgAction = super::ArgAction::Set;
        self.action.as_ref().unwrap_or(&DEFAULT)
    }

    /// Configured parser for argument values
    ///
    /// # Example
    ///
    /// ```rust
    /// let cmd = clap::Command::new("raw")
    ///     .arg(
    ///         clap::Arg::new("port")
    ///             .value_parser(clap::value_parser!(usize))
    ///     );
    /// let value_parser = cmd.get_arguments()
    ///     .find(|a| a.get_id() == "port").unwrap()
    ///     .get_value_parser();
    /// println!("{:?}", value_parser);
    /// ```
    pub fn get_value_parser(&self) -> &super::ValueParser {
        if let Some(value_parser) = self.value_parser.as_ref() {
            value_parser
        } else {
            static DEFAULT: super::ValueParser = super::ValueParser::string();
            &DEFAULT
        }
    }

    /// Report whether [`Arg::global`] is set
    pub fn is_global_set(&self) -> bool {
        self.is_set(ArgSettings::Global)
    }

    /// Report whether [`Arg::next_line_help`] is set
    pub fn is_next_line_help_set(&self) -> bool {
        self.is_set(ArgSettings::NextLineHelp)
    }

    /// Report whether [`Arg::hide`] is set
    pub fn is_hide_set(&self) -> bool {
        self.is_set(ArgSettings::Hidden)
    }

    /// Report whether [`Arg::hide_default_value`] is set
    pub fn is_hide_default_value_set(&self) -> bool {
        self.is_set(ArgSettings::HideDefaultValue)
    }

    /// Report whether [`Arg::hide_possible_values`] is set
    pub fn is_hide_possible_values_set(&self) -> bool {
        self.is_set(ArgSettings::HidePossibleValues)
    }

    /// Report whether [`Arg::hide_env`] is set
    #[cfg(feature = "env")]
    pub fn is_hide_env_set(&self) -> bool {
        self.is_set(ArgSettings::HideEnv)
    }

    /// Report whether [`Arg::hide_env_values`] is set
    #[cfg(feature = "env")]
    pub fn is_hide_env_values_set(&self) -> bool {
        self.is_set(ArgSettings::HideEnvValues)
    }

    /// Report whether [`Arg::hide_short_help`] is set
    pub fn is_hide_short_help_set(&self) -> bool {
        self.is_set(ArgSettings::HiddenShortHelp)
    }

    /// Report whether [`Arg::hide_long_help`] is set
    pub fn is_hide_long_help_set(&self) -> bool {
        self.is_set(ArgSettings::HiddenLongHelp)
    }

    /// Report whether [`Arg::require_equals`] is set
    pub fn is_require_equals_set(&self) -> bool {
        self.is_set(ArgSettings::RequireEquals)
    }

    /// Reports whether [`Arg::exclusive`] is set
    pub fn is_exclusive_set(&self) -> bool {
        self.is_set(ArgSettings::Exclusive)
    }

    /// Report whether [`Arg::trailing_var_arg`] is set
    pub fn is_trailing_var_arg_set(&self) -> bool {
        self.is_set(ArgSettings::TrailingVarArg)
    }

    /// Reports whether [`Arg::last`] is set
    pub fn is_last_set(&self) -> bool {
        self.is_set(ArgSettings::Last)
    }

    /// Reports whether [`Arg::ignore_case`] is set
    pub fn is_ignore_case_set(&self) -> bool {
        self.is_set(ArgSettings::IgnoreCase)
    }
}

/// # Internally used only
impl Arg {
    pub(crate) fn _build(&mut self) {
        if self.action.is_none() {
            if self.num_vals == Some(ValueRange::EMPTY) {
                let action = super::ArgAction::SetTrue;
                self.action = Some(action);
            } else {
                let action =
                    if self.is_positional() && self.num_vals.unwrap_or_default().is_unbounded() {
                        // Allow collecting arguments interleaved with flags
                        //
                        // Bounded values are probably a group and the user should explicitly opt-in to
                        // Append
                        super::ArgAction::Append
                    } else {
                        super::ArgAction::Set
                    };
                self.action = Some(action);
            }
        }
        if let Some(action) = self.action.as_ref() {
            if let Some(default_value) = action.default_value() {
                if self.default_vals.is_empty() {
                    self.default_vals = vec![default_value.into()];
                }
            }
            if let Some(default_value) = action.default_missing_value() {
                if self.default_missing_vals.is_empty() {
                    self.default_missing_vals = vec![default_value.into()];
                }
            }
        }

        if self.value_parser.is_none() {
            if let Some(default) = self.action.as_ref().and_then(|a| a.default_value_parser()) {
                self.value_parser = Some(default);
            } else {
                self.value_parser = Some(super::ValueParser::string());
            }
        }

        let val_names_len = self.val_names.len();
        if val_names_len > 1 {
            self.num_vals.get_or_insert(val_names_len.into());
        } else {
            let nargs = if self.get_action().takes_values() {
                ValueRange::SINGLE
            } else {
                ValueRange::EMPTY
            };
            self.num_vals.get_or_insert(nargs);
        }
    }

    // Used for positionals when printing
    pub(crate) fn name_no_brackets(&self) -> String {
        debug!("Arg::name_no_brackets:{}", self.get_id());
        let delim = " ";
        if !self.val_names.is_empty() {
            debug!("Arg::name_no_brackets: val_names={:#?}", self.val_names);

            if self.val_names.len() > 1 {
                self.val_names
                    .iter()
                    .map(|n| format!("<{}>", n))
                    .collect::<Vec<_>>()
                    .join(delim)
            } else {
                self.val_names
                    .first()
                    .expect(INTERNAL_ERROR_MSG)
                    .as_str()
                    .to_owned()
            }
        } else {
            debug!("Arg::name_no_brackets: just name");
            self.get_id().as_str().to_owned()
        }
    }

    pub(crate) fn stylized(&self, required: Option<bool>) -> StyledStr {
        let mut styled = StyledStr::new();
        // Write the name such --long or -l
        if let Some(l) = self.get_long() {
            styled.literal("--");
            styled.literal(l);
        } else if let Some(s) = self.get_short() {
            styled.literal("-");
            styled.literal(s);
        }
        styled.extend(self.stylize_arg_suffix(required).into_iter());
        styled
    }

src/output/usage.rs (line 160)

    fn needs_options_tag(&self) -> bool {
        debug!("Usage::needs_options_tag");
        'outer: for f in self.cmd.get_non_positionals() {
            debug!("Usage::needs_options_tag:iter: f={}", f.get_id());

            // Don't print `[OPTIONS]` just for help or version
            if f.get_long() == Some("help") || f.get_long() == Some("version") {
                debug!("Usage::needs_options_tag:iter Option is built-in");
                continue;
            }

            if f.is_hide_set() {
                debug!("Usage::needs_options_tag:iter Option is hidden");
                continue;
            }
            if f.is_required_set() {
                debug!("Usage::needs_options_tag:iter Option is required");
                continue;
            }
            for grp_s in self.cmd.groups_for_arg(f.get_id()) {
                debug!("Usage::needs_options_tag:iter:iter: grp_s={:?}", grp_s);
                if self.cmd.get_groups().any(|g| g.id == grp_s && g.required) {
                    debug!("Usage::needs_options_tag:iter:iter: Group is required");
                    continue 'outer;
                }
            }

            debug!("Usage::needs_options_tag:iter: [OPTIONS] required");
            return true;
        }

        debug!("Usage::needs_options_tag: [OPTIONS] not required");
        false
    }

src/parser/parser.rs (line 762)

    fn parse_long_arg(
        &mut self,
        matcher: &mut ArgMatcher,
        long_arg: Result<&str, &RawOsStr>,
        long_value: Option<&RawOsStr>,
        parse_state: &ParseState,
        pos_counter: usize,
        valid_arg_found: &mut bool,
    ) -> ClapResult<ParseResult> {
        // maybe here lifetime should be 'a
        debug!("Parser::parse_long_arg");

        #[allow(clippy::blocks_in_if_conditions)]
        if matches!(parse_state, ParseState::Opt(opt) | ParseState::Pos(opt) if
            self.cmd[opt].is_allow_hyphen_values_set())
        {
            debug!("Parser::parse_long_arg: prior arg accepts hyphenated values",);
            return Ok(ParseResult::MaybeHyphenValue);
        }

        debug!("Parser::parse_long_arg: Does it contain '='...");
        let long_arg = match long_arg {
            Ok(long_arg) => long_arg,
            Err(long_arg) => {
                return Ok(ParseResult::NoMatchingArg {
                    arg: long_arg.to_str_lossy().into_owned(),
                });
            }
        };
        if long_arg.is_empty() {
            debug_assert!(
                long_value.is_some(),
                "`--` should be filtered out before this point"
            );
        }

        let arg = if let Some(arg) = self.cmd.get_keymap().get(long_arg) {
            debug!("Parser::parse_long_arg: Found valid arg or flag '{}'", arg);
            Some((long_arg, arg))
        } else if self.cmd.is_infer_long_args_set() {
            self.cmd.get_arguments().find_map(|a| {
                if let Some(long) = a.get_long() {
                    if long.starts_with(long_arg) {
                        return Some((long, a));
                    }
                }
                a.aliases
                    .iter()
                    .find_map(|(alias, _)| alias.starts_with(long_arg).then(|| (alias.as_str(), a)))
            })
        } else {
            None
        };

        if let Some((_long_arg, arg)) = arg {
            let ident = Identifier::Long;
            *valid_arg_found = true;
            if arg.is_takes_value_set() {
                debug!(
                    "Parser::parse_long_arg({:?}): Found an arg with value '{:?}'",
                    long_arg, &long_value
                );
                let has_eq = long_value.is_some();
                self.parse_opt_value(ident, long_value, arg, matcher, has_eq)
            } else if let Some(rest) = long_value {
                let required = self.cmd.required_graph();
                debug!(
                    "Parser::parse_long_arg({:?}): Got invalid literal `{:?}`",
                    long_arg, rest
                );
                let mut used: Vec<Id> = matcher
                    .arg_ids()
                    .filter(|arg_id| {
                        matcher.check_explicit(arg_id, &crate::builder::ArgPredicate::IsPresent)
                    })
                    .filter(|&n| {
                        self.cmd.find(n).map_or(true, |a| {
                            !(a.is_hide_set() || required.contains(a.get_id()))
                        })
                    })
                    .cloned()
                    .collect();
                used.push(arg.get_id().clone());

                Ok(ParseResult::UnneededAttachedValue {
                    rest: rest.to_str_lossy().into_owned(),
                    used,
                    arg: arg.to_string(),
                })
            } else {
                debug!("Parser::parse_long_arg({:?}): Presence validated", long_arg);
                let trailing_idx = None;
                self.react(
                    Some(ident),
                    ValueSource::CommandLine,
                    arg,
                    vec![],
                    trailing_idx,
                    matcher,
                )
            }
        } else if let Some(sc_name) = self.possible_long_flag_subcommand(long_arg) {
            Ok(ParseResult::FlagSubCommand(sc_name.to_string()))
        } else if self
            .cmd
            .get_keymap()
            .get(&pos_counter)
            .map_or(false, |arg| {
                arg.is_allow_hyphen_values_set() && !arg.is_last_set()
            })
        {
            debug!(
                "Parser::parse_long_args: positional at {} allows hyphens",
                pos_counter
            );
            Ok(ParseResult::MaybeHyphenValue)
        } else {
            Ok(ParseResult::NoMatchingArg {
                arg: long_arg.to_owned(),
            })
        }
    }

src/builder/debug_asserts.rs (line 81)

pub(crate) fn assert_app(cmd: &Command) {
    debug!("Command::_debug_asserts");

    let mut short_flags = vec![];
    let mut long_flags = vec![];

    // Invalid version flag settings
    if cmd.get_version().is_none() && cmd.get_long_version().is_none() {
        // PropagateVersion is meaningless if there is no version
        assert!(
            !cmd.is_propagate_version_set(),
            "Command {}: No version information via Command::version or Command::long_version to propagate",
            cmd.get_name(),
        );

        // Used `Command::mut_arg("version", ..) but did not provide any version information to display
        let version_needed = cmd
            .get_arguments()
            .filter(|x| matches!(x.get_action(), ArgAction::Version))
            .map(|x| x.get_id())
            .collect::<Vec<_>>();

        assert_eq!(version_needed, Vec::<&str>::new(), "Command {}: `ArgAction::Version` used without providing Command::version or Command::long_version"
            ,cmd.get_name()
        );
    }

    for sc in cmd.get_subcommands() {
        if let Some(s) = sc.get_short_flag().as_ref() {
            short_flags.push(Flag::Command(format!("-{}", s), sc.get_name()));
        }

        for short_alias in sc.get_all_short_flag_aliases() {
            short_flags.push(Flag::Command(format!("-{}", short_alias), sc.get_name()));
        }

        if let Some(l) = sc.get_long_flag().as_ref() {
            assert!(!l.starts_with('-'), "Command {}: long_flag {:?} must not start with a `-`, that will be handled by the parser", sc.get_name(), l);
            long_flags.push(Flag::Command(format!("--{}", l), sc.get_name()));
        }

        for long_alias in sc.get_all_long_flag_aliases() {
            long_flags.push(Flag::Command(format!("--{}", long_alias), sc.get_name()));
        }
    }

    for arg in cmd.get_arguments() {
        assert_arg(arg);

        assert!(
            !cmd.is_multicall_set(),
            "Command {}: Arguments like {} cannot be set on a multicall command",
            cmd.get_name(),
            arg.get_id()
        );

        if let Some(s) = arg.get_short() {
            short_flags.push(Flag::Arg(format!("-{}", s), arg.get_id().as_str()));
        }

        for (short_alias, _) in &arg.short_aliases {
            short_flags.push(Flag::Arg(
                format!("-{}", short_alias),
                arg.get_id().as_str(),
            ));
        }

        if let Some(l) = arg.get_long() {
            assert!(!l.starts_with('-'), "Argument {}: long {:?} must not start with a `-`, that will be handled by the parser", arg.get_id(), l);
            long_flags.push(Flag::Arg(format!("--{}", l), arg.get_id().as_str()));
        }

        for (long_alias, _) in &arg.aliases {
            long_flags.push(Flag::Arg(
                format!("--{}", long_alias),
                arg.get_id().as_str(),
            ));
        }

        // Name conflicts
        if let Some((first, second)) = cmd.two_args_of(|x| x.get_id() == arg.get_id()) {
            panic!(
            "Command {}: Argument names must be unique, but '{}' is in use by more than one argument or group{}",
            cmd.get_name(),
            arg.get_id(),
            duplicate_tip(cmd, first, second),
        );
        }

        // Long conflicts
        if let Some(l) = arg.get_long() {
            if let Some((first, second)) = cmd.two_args_of(|x| x.get_long() == Some(l)) {
                panic!(
                    "Command {}: Long option names must be unique for each argument, \
                            but '--{}' is in use by both '{}' and '{}'{}",
                    cmd.get_name(),
                    l,
                    first.get_id(),
                    second.get_id(),
                    duplicate_tip(cmd, first, second)
                )
            }
        }

        // Short conflicts
        if let Some(s) = arg.get_short() {
            if let Some((first, second)) = cmd.two_args_of(|x| x.get_short() == Some(s)) {
                panic!(
                    "Command {}: Short option names must be unique for each argument, \
                            but '-{}' is in use by both '{}' and '{}'{}",
                    cmd.get_name(),
                    s,
                    first.get_id(),
                    second.get_id(),
                    duplicate_tip(cmd, first, second),
                )
            }
        }

        // Index conflicts
        if let Some(idx) = arg.index {
            if let Some((first, second)) =
                cmd.two_args_of(|x| x.is_positional() && x.get_index() == Some(idx))
            {
                panic!(
                    "Command {}: Argument '{}' has the same index as '{}' \
                    and they are both positional arguments\n\n\t \
                    Use `Arg::num_args(1..)` to allow one \
                    positional argument to take multiple values",
                    cmd.get_name(),
                    first.get_id(),
                    second.get_id()
                )
            }
        }

        // requires, r_if, r_unless
        for req in &arg.requires {
            assert!(
                cmd.id_exists(&req.1),
                "Command {}: Argument or group '{}' specified in 'requires*' for '{}' does not exist",
                cmd.get_name(),
                req.1,
                arg.get_id(),
            );
        }

        for req in &arg.r_ifs {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_if_eq*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(&req.0),
                "Command {}: Argument or group '{}' specified in 'required_if_eq*' for '{}' does not exist",
                    cmd.get_name(),
                req.0,
                arg.get_id()
            );
        }

        for req in &arg.r_ifs_all {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_if_eq_all`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(&req.0),
                "Command {}: Argument or group '{}' specified in 'required_if_eq_all' for '{}' does not exist",
                    cmd.get_name(),
                req.0,
                arg.get_id()
            );
        }

        for req in &arg.r_unless {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_unless*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'required_unless*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        for req in &arg.r_unless_all {
            assert!(
                !arg.is_required_set(),
                "Argument {}: `required` conflicts with `required_unless*`",
                arg.get_id()
            );
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'required_unless*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        // blacklist
        for req in &arg.blacklist {
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'conflicts_with*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        // overrides
        for req in &arg.overrides {
            assert!(
                cmd.id_exists(req),
                "Command {}: Argument or group '{}' specified in 'overrides_with*' for '{}' does not exist",
                    cmd.get_name(),
                req,
                arg.get_id(),
            );
        }

        if arg.is_last_set() {
            assert!(
                arg.get_long().is_none(),
                "Command {}: Flags or Options cannot have last(true) set. '{}' has both a long and last(true) set.",
                    cmd.get_name(),
                arg.get_id()
            );
            assert!(
                arg.get_short().is_none(),
                "Command {}: Flags or Options cannot have last(true) set. '{}' has both a short and last(true) set.",
                    cmd.get_name(),
                arg.get_id()
            );
        }

        assert!(
            !(arg.is_required_set() && arg.is_global_set()),
            "Command {}: Global arguments cannot be required.\n\n\t'{}' is marked as both global and required",
                    cmd.get_name(),
            arg.get_id()
        );

        if arg.get_value_hint() == ValueHint::CommandWithArguments {
            assert!(
                arg.is_positional(),
                "Command {}: Argument '{}' has hint CommandWithArguments and must be positional.",
                cmd.get_name(),
                arg.get_id()
            );

            assert!(
                arg.is_trailing_var_arg_set() || arg.is_last_set(),
                "Command {}: Positional argument '{}' has hint CommandWithArguments, so Command must have `trailing_var_arg(true)` or `last(true)` set.",
                    cmd.get_name(),
                arg.get_id()
            );
        }
    }

    for group in cmd.get_groups() {
        let derive_hint = if cfg!(feature = "derive") {
            " (note: `Args` implicitly creates `ArgGroup`s; disable with `#[group(skip)]`"
        } else {
            ""
        };

        // Name conflicts
        assert!(
            cmd.get_groups().filter(|x| x.id == group.id).count() < 2,
            "Command {}: Argument group name must be unique\n\n\t'{}' is already in use{}",
            cmd.get_name(),
            group.get_id(),
            derive_hint
        );

        // Groups should not have naming conflicts with Args
        assert!(
            !cmd.get_arguments().any(|x| x.get_id() == group.get_id()),
            "Command {}: Argument group name '{}' must not conflict with argument name{}",
            cmd.get_name(),
            group.get_id(),
            derive_hint
        );

        for arg in &group.args {
            // Args listed inside groups should exist
            assert!(
                cmd.get_arguments().any(|x| x.get_id() == arg),
                "Command {}: Argument group '{}' contains non-existent argument '{}'",
                cmd.get_name(),
                group.get_id(),
                arg
            );
        }
    }

    // Conflicts between flags and subcommands

    long_flags.sort_unstable();
    short_flags.sort_unstable();

    detect_duplicate_flags(&long_flags, "long");
    detect_duplicate_flags(&short_flags, "short");

    let mut subs = FlatSet::new();
    for sc in cmd.get_subcommands() {
        assert!(
            subs.insert(sc.get_name()),
            "Command {}: command name `{}` is duplicated",
            cmd.get_name(),
            sc.get_name()
        );
        for alias in sc.get_all_aliases() {
            assert!(
                subs.insert(alias),
                "Command {}: command `{}` alias `{}` is duplicated",
                cmd.get_name(),
                sc.get_name(),
                alias
            );
        }
    }

    _verify_positionals(cmd);

    #[cfg(feature = "help")]
    if let Some(help_template) = cmd.get_help_template() {
        assert!(
            !help_template.to_string().contains("{flags}"),
            "Command {}: {}",
                    cmd.get_name(),
            "`{flags}` template variable was removed in clap3, they are now included in `{options}`",
        );
        assert!(
            !help_template.to_string().contains("{unified}"),
            "Command {}: {}",
            cmd.get_name(),
            "`{unified}` template variable was removed in clap3, use `{options}` instead"
        );
    }

    cmd._panic_on_missing_help(cmd.is_help_expected_set());
    assert_app_flags(cmd);
}

pub fn get_visible_aliases(&self) -> Option<Vec<&str>>

Get visible aliases for this argument, if any

Examples found in repository

src/builder/arg.rs (line 3815)

    pub fn get_long_and_visible_aliases(&self) -> Option<Vec<&str>> {
        let mut longs = match self.get_long() {
            Some(long) => vec![long],
            None => return None,
        };
        if let Some(aliases) = self.get_visible_aliases() {
            longs.extend(aliases);
        }
        Some(longs)
    }

pub fn get_all_aliases(&self) -> Option<Vec<&str>>

Get all aliases for this argument, if any, both visible and hidden.

pub fn get_long_and_visible_aliases(&self) -> Option<Vec<&str>>

Get the long option name and its visible aliases, if any

pub fn get_possible_values(&self) -> Vec<PossibleValue>

Get the names of possible values for this argument. Only useful for user facing applications, such as building help messages or man files

Examples found in repository

src/builder/command.rs (line 4599)

    fn long_help_exists_(&self) -> bool {
        debug!("Command::long_help_exists");
        // In this case, both must be checked. This allows the retention of
        // original formatting, but also ensures that the actual -h or --help
        // specified by the user is sent through. If hide_short_help is not included,
        // then items specified with hidden_short_help will also be hidden.
        let should_long = |v: &Arg| {
            v.get_long_help().is_some()
                || v.is_hide_long_help_set()
                || v.is_hide_short_help_set()
                || v.get_possible_values()
                    .iter()
                    .any(PossibleValue::should_show_help)
        };

        // Subcommands aren't checked because we prefer short help for them, deferring to
        // `cmd subcmd --help` for more.
        self.get_long_about().is_some()
            || self.get_before_long_help().is_some()
            || self.get_after_long_help().is_some()
            || self.get_arguments().any(should_long)
    }

src/output/help_template.rs (line 602)

    fn help(
        &mut self,
        arg: Option<&Arg>,
        about: &StyledStr,
        spec_vals: &str,
        next_line_help: bool,
        longest: usize,
    ) {
        debug!("HelpTemplate::help");

        // Is help on next line, if so then indent
        if next_line_help {
            debug!("HelpTemplate::help: Next Line...{:?}", next_line_help);
            self.none("\n");
            self.none(TAB);
            self.none(NEXT_LINE_INDENT);
        }

        let spaces = if next_line_help {
            TAB.len() + NEXT_LINE_INDENT.len()
        } else if let Some(true) = arg.map(|a| a.is_positional()) {
            longest + TAB_WIDTH * 2
        } else {
            longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
        };
        let trailing_indent = spaces; // Don't indent any further than the first line is indented
        let trailing_indent = self.get_spaces(trailing_indent);

        let mut help = about.clone();
        replace_newline_var(&mut help);
        if !spec_vals.is_empty() {
            if !help.is_empty() {
                let sep = if self.use_long && arg.is_some() {
                    "\n\n"
                } else {
                    " "
                };
                help.none(sep);
            }
            help.none(spec_vals);
        }
        let avail_chars = self.term_w.saturating_sub(spaces);
        debug!(
            "HelpTemplate::help: help_width={}, spaces={}, avail={}",
            spaces,
            help.display_width(),
            avail_chars
        );
        help.wrap(avail_chars);
        help.indent("", &trailing_indent);
        let help_is_empty = help.is_empty();
        self.writer.extend(help.into_iter());
        if let Some(arg) = arg {
            const DASH_SPACE: usize = "- ".len();
            const COLON_SPACE: usize = ": ".len();
            let possible_vals = arg.get_possible_values();
            if self.use_long
                && !arg.is_hide_possible_values_set()
                && possible_vals.iter().any(PossibleValue::should_show_help)
            {
                debug!(
                    "HelpTemplate::help: Found possible vals...{:?}",
                    possible_vals
                );
                if !help_is_empty {
                    self.none("\n\n");
                    self.spaces(spaces);
                }
                self.none("Possible values:");
                let longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_quoted_name().map(|name| display_width(&name)))
                    .max()
                    .expect("Only called with possible value");
                let help_longest = possible_vals
                    .iter()
                    .filter_map(|f| f.get_visible_help().map(|h| h.display_width()))
                    .max()
                    .expect("Only called with possible value with help");
                // should new line
                let taken = longest + spaces + DASH_SPACE;

                let possible_value_new_line =
                    self.term_w >= taken && self.term_w < taken + COLON_SPACE + help_longest;

                let spaces = spaces + TAB_WIDTH - DASH_SPACE;
                let trailing_indent = if possible_value_new_line {
                    spaces + DASH_SPACE
                } else {
                    spaces + longest + DASH_SPACE + COLON_SPACE
                };
                let trailing_indent = self.get_spaces(trailing_indent);

                for pv in possible_vals.iter().filter(|pv| !pv.is_hide_set()) {
                    self.none("\n");
                    self.spaces(spaces);
                    self.none("- ");
                    self.literal(pv.get_name());
                    if let Some(help) = pv.get_help() {
                        debug!("HelpTemplate::help: Possible Value help");

                        if possible_value_new_line {
                            self.none(":\n");
                            self.spaces(trailing_indent.len());
                        } else {
                            self.none(": ");
                            // To align help messages
                            self.spaces(longest - display_width(pv.get_name()));
                        }

                        let avail_chars = if self.term_w > trailing_indent.len() {
                            self.term_w - trailing_indent.len()
                        } else {
                            usize::MAX
                        };

                        let mut help = help.clone();
                        replace_newline_var(&mut help);
                        help.wrap(avail_chars);
                        help.indent("", &trailing_indent);
                        self.writer.extend(help.into_iter());
                    }
                }
            }
        }
    }

    /// Will use next line help on writing args.
    fn will_args_wrap(&self, args: &[&Arg], longest: usize) -> bool {
        args.iter()
            .filter(|arg| should_show_arg(self.use_long, arg))
            .any(|arg| {
                let spec_vals = &self.spec_vals(arg);
                self.arg_next_line_help(arg, spec_vals, longest)
            })
    }

    fn arg_next_line_help(&self, arg: &Arg, spec_vals: &str, longest: usize) -> bool {
        if self.next_line_help || arg.is_next_line_help_set() || self.use_long {
            // setting_next_line
            true
        } else {
            // force_next_line
            let h = arg.get_help().unwrap_or_default();
            let h_w = h.display_width() + display_width(spec_vals);
            let taken = if arg.is_positional() {
                longest + TAB_WIDTH * 2
            } else {
                longest + TAB_WIDTH * 2 + 4 // See `fn short` for the 4
            };
            self.term_w >= taken
                && (taken as f32 / self.term_w as f32) > 0.40
                && h_w > (self.term_w - taken)
        }
    }

    fn spec_vals(&self, a: &Arg) -> String {
        debug!("HelpTemplate::spec_vals: a={}", a);
        let mut spec_vals = Vec::new();
        #[cfg(feature = "env")]
        if let Some(ref env) = a.env {
            if !a.is_hide_env_set() {
                debug!(
                    "HelpTemplate::spec_vals: Found environment variable...[{:?}:{:?}]",
                    env.0, env.1
                );
                let env_val = if !a.is_hide_env_values_set() {
                    format!(
                        "={}",
                        env.1
                            .as_ref()
                            .map(|s| s.to_string_lossy())
                            .unwrap_or_default()
                    )
                } else {
                    Default::default()
                };
                let env_info = format!("[env: {}{}]", env.0.to_string_lossy(), env_val);
                spec_vals.push(env_info);
            }
        }
        if a.is_takes_value_set() && !a.is_hide_default_value_set() && !a.default_vals.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found default value...[{:?}]",
                a.default_vals
            );

            let pvs = a
                .default_vals
                .iter()
                .map(|pvs| pvs.to_string_lossy())
                .map(|pvs| {
                    if pvs.contains(char::is_whitespace) {
                        Cow::from(format!("{:?}", pvs))
                    } else {
                        pvs
                    }
                })
                .collect::<Vec<_>>()
                .join(" ");

            spec_vals.push(format!("[default: {}]", pvs));
        }

        let als = a
            .aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|als| als.0.as_str()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!("HelpTemplate::spec_vals: Found aliases...{:?}", a.aliases);
            spec_vals.push(format!("[aliases: {}]", als));
        }

        let als = a
            .short_aliases
            .iter()
            .filter(|&als| als.1) // visible
            .map(|&als| als.0.to_string()) // name
            .collect::<Vec<_>>()
            .join(", ");
        if !als.is_empty() {
            debug!(
                "HelpTemplate::spec_vals: Found short aliases...{:?}",
                a.short_aliases
            );
            spec_vals.push(format!("[short aliases: {}]", als));
        }

        let possible_vals = a.get_possible_values();
        if !(a.is_hide_possible_values_set()
            || possible_vals.is_empty()
            || self.use_long && possible_vals.iter().any(PossibleValue::should_show_help))
        {
            debug!(
                "HelpTemplate::spec_vals: Found possible vals...{:?}",
                possible_vals
            );

            let pvs = possible_vals
                .iter()
                .filter_map(PossibleValue::get_visible_quoted_name)
                .collect::<Vec<_>>()
                .join(", ");

            spec_vals.push(format!("[possible values: {}]", pvs));
        }
        let connector = if self.use_long { "\n" } else { " " };
        spec_vals.join(connector)
    }

pub fn get_value_names(&self) -> Option<&[Str]>

Get the names of values for this argument.

Examples found in repository

src/builder/debug_asserts.rs (line 758)

fn assert_arg(arg: &Arg) {
    debug!("Arg::_debug_asserts:{}", arg.get_id());

    // Self conflict
    // TODO: this check should be recursive
    assert!(
        !arg.blacklist.iter().any(|x| x == arg.get_id()),
        "Argument '{}' cannot conflict with itself",
        arg.get_id(),
    );

    assert_eq!(
        arg.get_action().takes_values(),
        arg.is_takes_value_set(),
        "Argument `{}`'s selected action {:?} contradicts `takes_value`",
        arg.get_id(),
        arg.get_action()
    );
    if let Some(action_type_id) = arg.get_action().value_type_id() {
        assert_eq!(
            action_type_id,
            arg.get_value_parser().type_id(),
            "Argument `{}`'s selected action {:?} contradicts `value_parser` ({:?})",
            arg.get_id(),
            arg.get_action(),
            arg.get_value_parser()
        );
    }

    if arg.get_value_hint() != ValueHint::Unknown {
        assert!(
            arg.is_takes_value_set(),
            "Argument '{}' has value hint but takes no value",
            arg.get_id()
        );

        if arg.get_value_hint() == ValueHint::CommandWithArguments {
            assert!(
                arg.is_multiple_values_set(),
                "Argument '{}' uses hint CommandWithArguments and must accept multiple values",
                arg.get_id()
            )
        }
    }

    if arg.index.is_some() {
        assert!(
            arg.is_positional(),
            "Argument '{}' is a positional argument and can't have short or long name versions",
            arg.get_id()
        );
        assert!(
            arg.is_takes_value_set(),
            "Argument '{}` is positional, it must take a value{}",
            arg.get_id(),
            if arg.get_id() == Id::HELP {
                <