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pub struct ArgMatches { /* private fields */ }
Expand description

Container for parse results.

Used to get information about the arguments that were supplied to the program at runtime by the user. New instances of this struct are obtained by using the Command::get_matches family of methods.

Examples

let matches = Command::new("MyApp")
    .arg(Arg::new("out")
        .long("output")
        .required(true)
        .takes_value(true)
        .default_value("-"))
    .arg(Arg::new("cfg")
        .short('c')
        .takes_value(true))
    .get_matches(); // builds the instance of ArgMatches

// to get information about the "cfg" argument we created, such as the value supplied we use
// various ArgMatches methods, such as [ArgMatches::get_one]
if let Some(c) = matches.get_one::<String>("cfg") {
    println!("Value for -c: {}", c);
}

// The ArgMatches::get_one method returns an Option because the user may not have supplied
// that argument at runtime. But if we specified that the argument was "required" as we did
// with the "out" argument, we can safely unwrap because `clap` verifies that was actually
// used at runtime.
println!("Value for --output: {}", matches.get_one::<String>("out").unwrap());

// You can check the presence of an argument's values
if matches.contains_id("out") {
    // However, if you want to know where the value came from
    if matches.value_source("out").expect("checked contains_id") == ValueSource::CommandLine {
        println!("`out` set by user");
    } else {
        println!("`out` is defaulted");
    }
}

Implementations

Gets the value of a specific option or positional argument.

i.e. an argument that takes an additional value at runtime.

Returns an error if the wrong type was used.

Returns None if the option wasn’t present.

NOTE: This will always return Some(value) if default_value has been set. ArgMatches::value_source can be used to check if a value is present at runtime.

Panic

If the argument definition and access mismatch. To handle this case programmatically, see ArgMatches::try_get_one.

Examples
let m = Command::new("myapp")
    .arg(Arg::new("port")
        .value_parser(value_parser!(usize))
        .takes_value(true)
        .required(true))
    .get_matches_from(vec!["myapp", "2020"]);

let port: usize = *m
    .get_one("port")
    .expect("`port`is required");
assert_eq!(port, 2020);
Examples found in repository?
examples/tutorial_builder/03_03_positional.rs (line 8)
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fn main() {
    let matches = command!().arg(arg!([NAME])).get_matches();

    println!("NAME: {:?}", matches.get_one::<String>("NAME"));
}
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examples/tutorial_builder/03_02_option.rs (line 10)
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fn main() {
    let matches = command!()
        .arg(arg!(-n --name <NAME>).required(false))
        .get_matches();

    println!("name: {:?}", matches.get_one::<String>("name"));
}
examples/tutorial_builder/03_01_flag_count.rs (line 13)
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fn main() {
    let matches = command!()
        .arg(arg!(-v - -verbose).action(ArgAction::Count))
        .get_matches();

    println!(
        "verbose: {:?}",
        matches
            .get_one::<u8>("verbose")
            .expect("Count always defaulted")
    );
}
examples/tutorial_builder/03_05_default_values.rs (line 13)
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fn main() {
    let matches = command!()
        .arg(arg!([NAME]).default_value("alice"))
        .get_matches();

    println!(
        "NAME: {:?}",
        matches
            .get_one::<String>("NAME")
            .expect("default ensures there is always a value")
    );
}
examples/tutorial_builder/05_01_assert.rs (line 10)
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fn main() {
    let matches = cmd().get_matches();

    // Note, it's safe to call unwrap() because the arg is required
    let port: usize = *matches
        .get_one::<usize>("PORT")
        .expect("'PORT' is required and parsing will fail if its missing");
    println!("PORT = {}", port);
}
examples/derive_ref/flatten_hand_args.rs (line 18)
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    fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error> {
        Ok(Self {
            foo: *matches.get_one::<bool>("foo").expect("defaulted by clap"),
            bar: *matches.get_one::<bool>("bar").expect("defaulted by clap"),
            quuz: matches.remove_one::<String>("quuz"),
        })
    }
    fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error> {
        let mut matches = matches.clone();
        self.update_from_arg_matches_mut(&mut matches)
    }
    fn update_from_arg_matches_mut(&mut self, matches: &mut ArgMatches) -> Result<(), Error> {
        self.foo |= *matches.get_one::<bool>("foo").expect("defaulted by clap");
        self.bar |= *matches.get_one::<bool>("bar").expect("defaulted by clap");
        if let Some(quuz) = matches.remove_one::<String>("quuz") {
            self.quuz = Some(quuz);
        }
        Ok(())
    }

Iterate over values of a specific option or positional argument.

i.e. an argument that takes multiple values at runtime.

Returns an error if the wrong type was used.

Returns None if the option wasn’t present.

Panic

If the argument definition and access mismatch. To handle this case programmatically, see ArgMatches::try_get_many.

Examples
let m = Command::new("myprog")
    .arg(Arg::new("ports")
        .action(ArgAction::Append)
        .value_parser(value_parser!(usize))
        .short('p')
        .takes_value(true)
        .required(true))
    .get_matches_from(vec![
        "myprog", "-p", "22", "-p", "80", "-p", "2020"
    ]);
let vals: Vec<usize> = m.get_many("ports")
    .expect("`port`is required")
    .copied()
    .collect();
assert_eq!(vals, [22, 80, 2020]);
Examples found in repository?
examples/escaped-positional.rs (line 35)
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fn main() {
    let matches = command!()
        .arg(arg!(eff: -f).action(ArgAction::SetTrue))
        .arg(
            arg!(pea: -p <PEAR>)
                .required(false)
                .value_parser(value_parser!(String)),
        )
        .arg(
            // Indicates that `slop` is only accessible after `--`.
            arg!(slop: [SLOP])
                .multiple_values(true)
                .last(true)
                .value_parser(value_parser!(String)),
        )
        .get_matches();

    // This is what will happen with `myprog -f -p=bob -- sloppy slop slop`...

    // -f used: true
    println!(
        "-f used: {:?}",
        *matches.get_one::<bool>("eff").expect("defaulted by clap")
    );
    // -p's value: Some("bob")
    println!("-p's value: {:?}", matches.get_one::<String>("pea"));
    // 'slops' values: Some(["sloppy", "slop", "slop"])
    println!(
        "'slops' values: {:?}",
        matches
            .get_many::<String>("slop")
            .map(|vals| vals.collect::<Vec<_>>())
            .unwrap_or_default()
    );

    // Continued program logic goes here...
}
More examples
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examples/git.rs (line 65)
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fn main() {
    let matches = cli().get_matches();

    match matches.subcommand() {
        Some(("clone", sub_matches)) => {
            println!(
                "Cloning {}",
                sub_matches.get_one::<String>("REMOTE").expect("required")
            );
        }
        Some(("push", sub_matches)) => {
            println!(
                "Pushing to {}",
                sub_matches.get_one::<String>("REMOTE").expect("required")
            );
        }
        Some(("add", sub_matches)) => {
            let paths = sub_matches
                .get_many::<PathBuf>("PATH")
                .into_iter()
                .flatten()
                .collect::<Vec<_>>();
            println!("Adding {:?}", paths);
        }
        Some(("stash", sub_matches)) => {
            let stash_command = sub_matches.subcommand().unwrap_or(("push", sub_matches));
            match stash_command {
                ("apply", sub_matches) => {
                    let stash = sub_matches.get_one::<String>("STASH");
                    println!("Applying {:?}", stash);
                }
                ("pop", sub_matches) => {
                    let stash = sub_matches.get_one::<String>("STASH");
                    println!("Popping {:?}", stash);
                }
                ("push", sub_matches) => {
                    let message = sub_matches.get_one::<String>("message");
                    println!("Pushing {:?}", message);
                }
                (name, _) => {
                    unreachable!("Unsupported subcommand `{}`", name)
                }
            }
        }
        Some((ext, sub_matches)) => {
            let args = sub_matches
                .get_many::<OsString>("")
                .into_iter()
                .flatten()
                .collect::<Vec<_>>();
            println!("Calling out to {:?} with {:?}", ext, args);
        }
        _ => unreachable!(), // If all subcommands are defined above, anything else is unreachabe!()
    }

    // Continued program logic goes here...
}
examples/pacman.rs (line 76)
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fn main() {
    let matches = Command::new("pacman")
        .about("package manager utility")
        .version("5.2.1")
        .subcommand_required(true)
        .arg_required_else_help(true)
        .author("Pacman Development Team")
        // Query subcommand
        //
        // Only a few of its arguments are implemented below.
        .subcommand(
            Command::new("query")
                .short_flag('Q')
                .long_flag("query")
                .about("Query the package database.")
                .arg(
                    Arg::new("search")
                        .short('s')
                        .long("search")
                        .help("search locally installed packages for matching strings")
                        .conflicts_with("info")
                        .takes_value(true)
                        .multiple_values(true),
                )
                .arg(
                    Arg::new("info")
                        .long("info")
                        .short('i')
                        .conflicts_with("search")
                        .help("view package information")
                        .takes_value(true)
                        .multiple_values(true),
                ),
        )
        // Sync subcommand
        //
        // Only a few of its arguments are implemented below.
        .subcommand(
            Command::new("sync")
                .short_flag('S')
                .long_flag("sync")
                .about("Synchronize packages.")
                .arg(
                    Arg::new("search")
                        .short('s')
                        .long("search")
                        .conflicts_with("info")
                        .takes_value(true)
                        .multiple_values(true)
                        .help("search remote repositories for matching strings"),
                )
                .arg(
                    Arg::new("info")
                        .long("info")
                        .conflicts_with("search")
                        .short('i')
                        .action(ArgAction::SetTrue)
                        .help("view package information"),
                )
                .arg(
                    Arg::new("package")
                        .help("packages")
                        .required_unless_present("search")
                        .takes_value(true)
                        .multiple_values(true),
                ),
        )
        .get_matches();

    match matches.subcommand() {
        Some(("sync", sync_matches)) => {
            if sync_matches.contains_id("search") {
                let packages: Vec<_> = sync_matches
                    .get_many::<String>("search")
                    .expect("contains_id")
                    .map(|s| s.as_str())
                    .collect();
                let values = packages.join(", ");
                println!("Searching for {}...", values);
                return;
            }

            let packages: Vec<_> = sync_matches
                .get_many::<String>("package")
                .expect("is present")
                .map(|s| s.as_str())
                .collect();
            let values = packages.join(", ");

            if *sync_matches
                .get_one::<bool>("info")
                .expect("defaulted by clap")
            {
                println!("Retrieving info for {}...", values);
            } else {
                println!("Installing {}...", values);
            }
        }
        Some(("query", query_matches)) => {
            if let Some(packages) = query_matches.get_many::<String>("info") {
                let comma_sep = packages.map(|s| s.as_str()).collect::<Vec<_>>().join(", ");
                println!("Retrieving info for {}...", comma_sep);
            } else if let Some(queries) = query_matches.get_many::<String>("search") {
                let comma_sep = queries.map(|s| s.as_str()).collect::<Vec<_>>().join(", ");
                println!("Searching Locally for {}...", comma_sep);
            } else {
                println!("Displaying all locally installed packages...");
            }
        }
        _ => unreachable!(), // If all subcommands are defined above, anything else is unreachable
    }
}

Iterate over the original argument values.

An OsStr on Unix-like systems is any series of bytes, regardless of whether or not they contain valid UTF-8. Since Strings in Rust are guaranteed to be valid UTF-8, a valid filename on a Unix system as an argument value may contain invalid UTF-8.

Returns None if the option wasn’t present.

Panic

If the argument definition and access mismatch. To handle this case programmatically, see ArgMatches::try_get_raw.

Examples
use std::path::PathBuf;

let m = Command::new("utf8")
   .arg(arg!(<arg> ... "some arg").value_parser(value_parser!(PathBuf)))
   .get_matches_from(vec![OsString::from("myprog"),
                               // "Hi"
                               OsString::from_vec(vec![b'H', b'i']),
                               // "{0xe9}!"
                               OsString::from_vec(vec![0xe9, b'!'])]);

let mut itr = m.get_raw("arg")
   .expect("`port`is required")
   .into_iter();
assert_eq!(itr.next(), Some(OsStr::new("Hi")));
assert_eq!(itr.next(), Some(OsStr::from_bytes(&[0xe9, b'!'])));
assert_eq!(itr.next(), None);

Returns the value of a specific option or positional argument.

i.e. an argument that takes an additional value at runtime.

Returns an error if the wrong type was used. No item will have been removed.

Returns None if the option wasn’t present.

NOTE: This will always return Some(value) if default_value has been set. ArgMatches::value_source can be used to check if a value is present at runtime.

Panic

If the argument definition and access mismatch. To handle this case programmatically, see ArgMatches::try_remove_one.

Examples
let mut m = Command::new("myprog")
    .arg(Arg::new("file")
        .required(true)
        .takes_value(true))
    .get_matches_from(vec![
        "myprog", "file.txt",
    ]);
let vals: String = m.remove_one("file")
    .expect("`file`is required");
assert_eq!(vals, "file.txt");
Examples found in repository?
examples/derive_ref/flatten_hand_args.rs (line 20)
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    fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error> {
        Ok(Self {
            foo: *matches.get_one::<bool>("foo").expect("defaulted by clap"),
            bar: *matches.get_one::<bool>("bar").expect("defaulted by clap"),
            quuz: matches.remove_one::<String>("quuz"),
        })
    }
    fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error> {
        let mut matches = matches.clone();
        self.update_from_arg_matches_mut(&mut matches)
    }
    fn update_from_arg_matches_mut(&mut self, matches: &mut ArgMatches) -> Result<(), Error> {
        self.foo |= *matches.get_one::<bool>("foo").expect("defaulted by clap");
        self.bar |= *matches.get_one::<bool>("bar").expect("defaulted by clap");
        if let Some(quuz) = matches.remove_one::<String>("quuz") {
            self.quuz = Some(quuz);
        }
        Ok(())
    }

Return values of a specific option or positional argument.

i.e. an argument that takes multiple values at runtime.

Returns an error if the wrong type was used. No item will have been removed.

Returns None if the option wasn’t present.

Panic

If the argument definition and access mismatch. To handle this case programmatically, see ArgMatches::try_remove_many.

Examples
let mut m = Command::new("myprog")
    .arg(Arg::new("file")
        .action(ArgAction::Append)
        .multiple_values(true)
        .required(true)
        .takes_value(true))
    .get_matches_from(vec![
        "myprog", "file1.txt", "file2.txt", "file3.txt", "file4.txt",
    ]);
let vals: Vec<String> = m.remove_many("file")
    .expect("`file`is required")
    .collect();
assert_eq!(vals, ["file1.txt", "file2.txt", "file3.txt", "file4.txt"]);

Check if values are present for the argument or group id

NOTE: This will always return true if default_value has been set. ArgMatches::value_source can be used to check if a value is present at runtime.

Panics

If id is is not a valid argument or group name. To handle this case programmatically, see ArgMatches::try_contains_id.

Examples
let m = Command::new("myprog")
    .arg(Arg::new("debug")
        .short('d'))
    .get_matches_from(vec![
        "myprog", "-d"
    ]);

assert!(m.contains_id("debug"));
Examples found in repository?
examples/multicall-busybox.rs (line 38)
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fn main() {
    let cmd = Command::new(env!("CARGO_CRATE_NAME"))
        .multicall(true)
        .subcommand(
            Command::new("busybox")
                .arg_required_else_help(true)
                .subcommand_value_name("APPLET")
                .subcommand_help_heading("APPLETS")
                .arg(
                    Arg::new("install")
                        .long("install")
                        .help("Install hardlinks for all subcommands in path")
                        .exclusive(true)
                        .takes_value(true)
                        .default_missing_value("/usr/local/bin")
                        .value_parser(value_parser!(PathBuf))
                        .use_value_delimiter(false),
                )
                .subcommands(applet_commands()),
        )
        .subcommands(applet_commands());

    let matches = cmd.get_matches();
    let mut subcommand = matches.subcommand();
    if let Some(("busybox", cmd)) = subcommand {
        if cmd.contains_id("install") {
            unimplemented!("Make hardlinks to the executable here");
        }
        subcommand = cmd.subcommand();
    }
    match subcommand {
        Some(("false", _)) => exit(1),
        Some(("true", _)) => exit(0),
        _ => unreachable!("parser should ensure only valid subcommand names are used"),
    }
}
More examples
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examples/tutorial_builder/04_03_relations.rs (line 71)
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fn main() {
    // Create application like normal
    let matches = command!()
        // Add the version arguments
        .arg(arg!(--"set-ver" <VER> "set version manually").required(false))
        .arg(arg!(--major         "auto inc major").action(ArgAction::SetTrue))
        .arg(arg!(--minor         "auto inc minor").action(ArgAction::SetTrue))
        .arg(arg!(--patch         "auto inc patch").action(ArgAction::SetTrue))
        // Create a group, make it required, and add the above arguments
        .group(
            ArgGroup::new("vers")
                .required(true)
                .args(&["set-ver", "major", "minor", "patch"]),
        )
        // Arguments can also be added to a group individually, these two arguments
        // are part of the "input" group which is not required
        .arg(
            arg!([INPUT_FILE] "some regular input")
                .value_parser(value_parser!(PathBuf))
                .group("input"),
        )
        .arg(
            arg!(--"spec-in" <SPEC_IN> "some special input argument")
                .required(false)
                .value_parser(value_parser!(PathBuf))
                .group("input"),
        )
        // Now let's assume we have a -c [config] argument which requires one of
        // (but **not** both) the "input" arguments
        .arg(
            arg!(config: -c <CONFIG>)
                .required(false)
                .value_parser(value_parser!(PathBuf))
                .requires("input"),
        )
        .get_matches();

    // Let's assume the old version 1.2.3
    let mut major = 1;
    let mut minor = 2;
    let mut patch = 3;

    // See if --set-ver was used to set the version manually
    let version = if let Some(ver) = matches.get_one::<String>("set-ver") {
        ver.to_owned()
    } else {
        // Increment the one requested (in a real program, we'd reset the lower numbers)
        let (maj, min, pat) = (
            *matches.get_one::<bool>("major").expect("defaulted by clap"),
            *matches.get_one::<bool>("minor").expect("defaulted by clap"),
            *matches.get_one::<bool>("patch").expect("defaulted by clap"),
        );
        match (maj, min, pat) {
            (true, _, _) => major += 1,
            (_, true, _) => minor += 1,
            (_, _, true) => patch += 1,
            _ => unreachable!(),
        };
        format!("{}.{}.{}", major, minor, patch)
    };

    println!("Version: {}", version);

    // Check for usage of -c
    if matches.contains_id("config") {
        let input = matches
            .get_one::<PathBuf>("INPUT_FILE")
            .unwrap_or_else(|| matches.get_one::<PathBuf>("spec-in").unwrap())
            .display();
        println!(
            "Doing work using input {} and config {}",
            input,
            matches.get_one::<PathBuf>("config").unwrap().display()
        );
    }
}
examples/tutorial_builder/04_04_custom.rs (line 75)
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fn main() {
    // Create application like normal
    let mut cmd = command!()
        // Add the version arguments
        .arg(arg!(--"set-ver" <VER> "set version manually").required(false))
        .arg(arg!(--major         "auto inc major").action(ArgAction::SetTrue))
        .arg(arg!(--minor         "auto inc minor").action(ArgAction::SetTrue))
        .arg(arg!(--patch         "auto inc patch").action(ArgAction::SetTrue))
        // Arguments can also be added to a group individually, these two arguments
        // are part of the "input" group which is not required
        .arg(arg!([INPUT_FILE] "some regular input").value_parser(value_parser!(PathBuf)))
        .arg(
            arg!(--"spec-in" <SPEC_IN> "some special input argument")
                .required(false)
                .value_parser(value_parser!(PathBuf)),
        )
        // Now let's assume we have a -c [config] argument which requires one of
        // (but **not** both) the "input" arguments
        .arg(
            arg!(config: -c <CONFIG>)
                .required(false)
                .value_parser(value_parser!(PathBuf)),
        );
    let matches = cmd.get_matches_mut();

    // Let's assume the old version 1.2.3
    let mut major = 1;
    let mut minor = 2;
    let mut patch = 3;

    // See if --set-ver was used to set the version manually
    let version = if let Some(ver) = matches.get_one::<String>("set-ver") {
        if *matches.get_one::<bool>("major").expect("defaulted by clap")
            || *matches.get_one::<bool>("minor").expect("defaulted by clap")
            || *matches.get_one::<bool>("patch").expect("defaulted by clap")
        {
            cmd.error(
                ErrorKind::ArgumentConflict,
                "Can't do relative and absolute version change",
            )
            .exit();
        }
        ver.to_string()
    } else {
        // Increment the one requested (in a real program, we'd reset the lower numbers)
        let (maj, min, pat) = (
            *matches.get_one::<bool>("major").expect("defaulted by clap"),
            *matches.get_one::<bool>("minor").expect("defaulted by clap"),
            *matches.get_one::<bool>("patch").expect("defaulted by clap"),
        );
        match (maj, min, pat) {
            (true, false, false) => major += 1,
            (false, true, false) => minor += 1,
            (false, false, true) => patch += 1,
            _ => {
                cmd.error(
                    ErrorKind::ArgumentConflict,
                    "Can only modify one version field",
                )
                .exit();
            }
        };
        format!("{}.{}.{}", major, minor, patch)
    };

    println!("Version: {}", version);

    // Check for usage of -c
    if matches.contains_id("config") {
        let input = matches
            .get_one::<PathBuf>("INPUT_FILE")
            .or_else(|| matches.get_one::<PathBuf>("spec-in"))
            .unwrap_or_else(|| {
                cmd.error(
                    ErrorKind::MissingRequiredArgument,
                    "INPUT_FILE or --spec-in is required when using --config",
                )
                .exit()
            })
            .display();
        println!(
            "Doing work using input {} and config {}",
            input,
            matches.get_one::<PathBuf>("config").unwrap().display()
        );
    }
}
examples/pacman.rs (line 74)
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fn main() {
    let matches = Command::new("pacman")
        .about("package manager utility")
        .version("5.2.1")
        .subcommand_required(true)
        .arg_required_else_help(true)
        .author("Pacman Development Team")
        // Query subcommand
        //
        // Only a few of its arguments are implemented below.
        .subcommand(
            Command::new("query")
                .short_flag('Q')
                .long_flag("query")
                .about("Query the package database.")
                .arg(
                    Arg::new("search")
                        .short('s')
                        .long("search")
                        .help("search locally installed packages for matching strings")
                        .conflicts_with("info")
                        .takes_value(true)
                        .multiple_values(true),
                )
                .arg(
                    Arg::new("info")
                        .long("info")
                        .short('i')
                        .conflicts_with("search")
                        .help("view package information")
                        .takes_value(true)
                        .multiple_values(true),
                ),
        )
        // Sync subcommand
        //
        // Only a few of its arguments are implemented below.
        .subcommand(
            Command::new("sync")
                .short_flag('S')
                .long_flag("sync")
                .about("Synchronize packages.")
                .arg(
                    Arg::new("search")
                        .short('s')
                        .long("search")
                        .conflicts_with("info")
                        .takes_value(true)
                        .multiple_values(true)
                        .help("search remote repositories for matching strings"),
                )
                .arg(
                    Arg::new("info")
                        .long("info")
                        .conflicts_with("search")
                        .short('i')
                        .action(ArgAction::SetTrue)
                        .help("view package information"),
                )
                .arg(
                    Arg::new("package")
                        .help("packages")
                        .required_unless_present("search")
                        .takes_value(true)
                        .multiple_values(true),
                ),
        )
        .get_matches();

    match matches.subcommand() {
        Some(("sync", sync_matches)) => {
            if sync_matches.contains_id("search") {
                let packages: Vec<_> = sync_matches
                    .get_many::<String>("search")
                    .expect("contains_id")
                    .map(|s| s.as_str())
                    .collect();
                let values = packages.join(", ");
                println!("Searching for {}...", values);
                return;
            }

            let packages: Vec<_> = sync_matches
                .get_many::<String>("package")
                .expect("is present")
                .map(|s| s.as_str())
                .collect();
            let values = packages.join(", ");

            if *sync_matches
                .get_one::<bool>("info")
                .expect("defaulted by clap")
            {
                println!("Retrieving info for {}...", values);
            } else {
                println!("Installing {}...", values);
            }
        }
        Some(("query", query_matches)) => {
            if let Some(packages) = query_matches.get_many::<String>("info") {
                let comma_sep = packages.map(|s| s.as_str()).collect::<Vec<_>>().join(", ");
                println!("Retrieving info for {}...", comma_sep);
            } else if let Some(queries) = query_matches.get_many::<String>("search") {
                let comma_sep = queries.map(|s| s.as_str()).collect::<Vec<_>>().join(", ");
                println!("Searching Locally for {}...", comma_sep);
            } else {
                println!("Displaying all locally installed packages...");
            }
        }
        _ => unreachable!(), // If all subcommands are defined above, anything else is unreachable
    }
}

Check if any args were present on the command line

Examples
let mut cmd = Command::new("myapp")
    .arg(Arg::new("output")
        .takes_value(true));

let m = cmd
    .try_get_matches_from_mut(vec!["myapp", "something"])
    .unwrap();
assert!(m.args_present());

let m = cmd
    .try_get_matches_from_mut(vec!["myapp"])
    .unwrap();
assert!(! m.args_present());

Deprecated, replaced with ArgMatches::get_one()

Deprecated, replaced with ArgMatches::get_one()

Deprecated, replaced with ArgMatches::get_one()

Deprecated, replaced with ArgMatches::get_many()

Available on crate feature unstable-grouped only.

Get an Iterator over groups of values of a specific option.

specifically grouped by the occurrences of the options.

Each group is a Vec<&str> containing the arguments passed to a single occurrence of the option.

If the option doesn’t support multiple occurrences, or there was only a single occurrence, the iterator will only contain a single item.

Returns None if the option wasn’t present.

Panics

If the value is invalid UTF-8.

If id is not a valid argument or group id.

Examples
let m = Command::new("myprog")
    .arg(Arg::new("exec")
        .short('x')
        .min_values(1)
        .action(ArgAction::Append)
        .value_terminator(";"))
    .get_matches_from(vec![
        "myprog", "-x", "echo", "hi", ";", "-x", "echo", "bye"]);
let vals: Vec<Vec<&str>> = m.grouped_values_of("exec").unwrap().collect();
assert_eq!(vals, [["echo", "hi"], ["echo", "bye"]]);

Deprecated, replaced with ArgMatches::get_many()

Deprecated, replaced with ArgMatches::get_many()

Deprecated, replaced with ArgMatches::get_one()

Deprecated, replaced with ArgMatches::get_one()

Deprecated, replaced with ArgMatches::get_many()

Deprecated, replaced with ArgMatches::get_many()

Deprecated, replaced with ArgAction::SetTrue or ArgMatches::contains_id.

Report where argument value came from

Panics

If id is is not a valid argument or group id.

Examples
let m = Command::new("myprog")
    .arg(Arg::new("debug")
        .short('d'))
    .get_matches_from(vec![
        "myprog", "-d"
    ]);

assert_eq!(m.value_source("debug"), Some(ValueSource::CommandLine));

Deprecated, replaced with ArgAction::Count or ArgMatches::get_many.len().

The first index of that an argument showed up.

Indices are similar to argv indices, but are not exactly 1:1.

For flags (i.e. those arguments which don’t have an associated value), indices refer to occurrence of the switch, such as -f, or --flag. However, for options the indices refer to the values -o val would therefore not represent two distinct indices, only the index for val would be recorded. This is by design.

Besides the flag/option discrepancy, the primary difference between an argv index and clap index, is that clap continues counting once all arguments have properly separated, whereas an argv index does not.

The examples should clear this up.

NOTE: If an argument is allowed multiple times, this method will only give the first index. See ArgMatches::indices_of.

Panics

If id is is not a valid argument or group id.

Examples

The argv indices are listed in the comments below. See how they correspond to the clap indices. Note that if it’s not listed in a clap index, this is because it’s not saved in in an ArgMatches struct for querying.

let m = Command::new("myapp")
    .arg(Arg::new("flag")
        .short('f'))
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true))
    .get_matches_from(vec!["myapp", "-f", "-o", "val"]);
           // ARGV indices: ^0       ^1    ^2    ^3
           // clap indices:          ^1          ^3

assert_eq!(m.index_of("flag"), Some(1));
assert_eq!(m.index_of("option"), Some(3));

Now notice, if we use one of the other styles of options:

let m = Command::new("myapp")
    .arg(Arg::new("flag")
        .short('f'))
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true))
    .get_matches_from(vec!["myapp", "-f", "-o=val"]);
           // ARGV indices: ^0       ^1    ^2
           // clap indices:          ^1       ^3

assert_eq!(m.index_of("flag"), Some(1));
assert_eq!(m.index_of("option"), Some(3));

Things become much more complicated, or clear if we look at a more complex combination of flags. Let’s also throw in the final option style for good measure.

let m = Command::new("myapp")
    .arg(Arg::new("flag")
        .short('f'))
    .arg(Arg::new("flag2")
        .short('F'))
    .arg(Arg::new("flag3")
        .short('z'))
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true))
    .get_matches_from(vec!["myapp", "-fzF", "-oval"]);
           // ARGV indices: ^0      ^1       ^2
           // clap indices:         ^1,2,3    ^5
           //
           // clap sees the above as 'myapp -f -z -F -o val'
           //                         ^0    ^1 ^2 ^3 ^4 ^5
assert_eq!(m.index_of("flag"), Some(1));
assert_eq!(m.index_of("flag2"), Some(3));
assert_eq!(m.index_of("flag3"), Some(2));
assert_eq!(m.index_of("option"), Some(5));

One final combination of flags/options to see how they combine:

let m = Command::new("myapp")
    .arg(Arg::new("flag")
        .short('f'))
    .arg(Arg::new("flag2")
        .short('F'))
    .arg(Arg::new("flag3")
        .short('z'))
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true))
    .get_matches_from(vec!["myapp", "-fzFoval"]);
           // ARGV indices: ^0       ^1
           // clap indices:          ^1,2,3^5
           //
           // clap sees the above as 'myapp -f -z -F -o val'
           //                         ^0    ^1 ^2 ^3 ^4 ^5
assert_eq!(m.index_of("flag"), Some(1));
assert_eq!(m.index_of("flag2"), Some(3));
assert_eq!(m.index_of("flag3"), Some(2));
assert_eq!(m.index_of("option"), Some(5));

The last part to mention is when values are sent in multiple groups with a delimiter.

let m = Command::new("myapp")
    .arg(Arg::new("option")
        .short('o')
        .use_value_delimiter(true)
        .multiple_values(true))
    .get_matches_from(vec!["myapp", "-o=val1,val2,val3"]);
           // ARGV indices: ^0       ^1
           // clap indices:             ^2   ^3   ^4
           //
           // clap sees the above as 'myapp -o val1 val2 val3'
           //                         ^0    ^1 ^2   ^3   ^4
assert_eq!(m.index_of("option"), Some(2));
assert_eq!(m.indices_of("option").unwrap().collect::<Vec<_>>(), &[2, 3, 4]);

All indices an argument appeared at when parsing.

Indices are similar to argv indices, but are not exactly 1:1.

For flags (i.e. those arguments which don’t have an associated value), indices refer to occurrence of the switch, such as -f, or --flag. However, for options the indices refer to the values -o val would therefore not represent two distinct indices, only the index for val would be recorded. This is by design.

NOTE: For more information about how clap indices compared to argv indices, see ArgMatches::index_of

Panics

If id is is not a valid argument or group id.

Examples
let m = Command::new("myapp")
    .arg(Arg::new("option")
        .short('o')
        .use_value_delimiter(true)
        .multiple_values(true))
    .get_matches_from(vec!["myapp", "-o=val1,val2,val3"]);
           // ARGV indices: ^0       ^1
           // clap indices:             ^2   ^3   ^4
           //
           // clap sees the above as 'myapp -o val1 val2 val3'
           //                         ^0    ^1 ^2   ^3   ^4
assert_eq!(m.indices_of("option").unwrap().collect::<Vec<_>>(), &[2, 3, 4]);

Another quick example is when flags and options are used together

let m = Command::new("myapp")
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true)
        .action(ArgAction::Append))
    .arg(Arg::new("flag")
        .short('f')
        .action(ArgAction::Count))
    .get_matches_from(vec!["myapp", "-o", "val1", "-f", "-o", "val2", "-f"]);
           // ARGV indices: ^0       ^1    ^2      ^3    ^4    ^5      ^6
           // clap indices:                ^2      ^3          ^5      ^6

assert_eq!(m.indices_of("option").unwrap().collect::<Vec<_>>(), &[2, 5]);
assert_eq!(m.indices_of("flag").unwrap().collect::<Vec<_>>(), &[6]);

One final example, which is an odd case; if we don’t use value delimiter as we did with the first example above instead of val1, val2 and val3 all being distinc values, they would all be a single value of val1,val2,val3, in which case they’d only receive a single index.

let m = Command::new("myapp")
    .arg(Arg::new("option")
        .short('o')
        .takes_value(true)
        .multiple_values(true))
    .get_matches_from(vec!["myapp", "-o=val1,val2,val3"]);
           // ARGV indices: ^0       ^1
           // clap indices:             ^2
           //
           // clap sees the above as 'myapp -o "val1,val2,val3"'
           //                         ^0    ^1  ^2
assert_eq!(m.indices_of("option").unwrap().collect::<Vec<_>>(), &[2]);

The name and ArgMatches of the current subcommand.

Subcommand values are put in a child ArgMatches

Returns None if the subcommand wasn’t present at runtime,

Examples
 let app_m = Command::new("git")
     .subcommand(Command::new("clone"))
     .subcommand(Command::new("push"))
     .subcommand(Command::new("commit"))
     .get_matches();

match app_m.subcommand() {
    Some(("clone",  sub_m)) => {}, // clone was used
    Some(("push",   sub_m)) => {}, // push was used
    Some(("commit", sub_m)) => {}, // commit was used
    _                       => {}, // Either no subcommand or one not tested for...
}

Another useful scenario is when you want to support third party, or external, subcommands. In these cases you can’t know the subcommand name ahead of time, so use a variable instead with pattern matching!

// Assume there is an external subcommand named "subcmd"
let app_m = Command::new("myprog")
    .allow_external_subcommands(true)
    .get_matches_from(vec![
        "myprog", "subcmd", "--option", "value", "-fff", "--flag"
    ]);

// All trailing arguments will be stored under the subcommand's sub-matches using an empty
// string argument name
match app_m.subcommand() {
    Some((external, sub_m)) => {
         let ext_args: Vec<&str> = sub_m.get_many::<String>("")
            .unwrap().map(|s| s.as_str()).collect();
         assert_eq!(external, "subcmd");
         assert_eq!(ext_args, ["--option", "value", "-fff", "--flag"]);
    },
    _ => {},
}
Examples found in repository?
examples/tutorial_builder/03_04_subcommands.rs (line 17)
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fn main() {
    let matches = command!()
        .propagate_version(true)
        .subcommand_required(true)
        .arg_required_else_help(true)
        .subcommand(
            Command::new("add")
                .about("Adds files to myapp")
                .arg(arg!([NAME])),
        )
        .get_matches();

    match matches.subcommand() {
        Some(("add", sub_matches)) => println!(
            "'myapp add' was used, name is: {:?}",
            sub_matches.get_one::<String>("NAME")
        ),
        _ => unreachable!("Exhausted list of subcommands and subcommand_required prevents `None`"),
    }
}
More examples
Hide additional examples
examples/derive_ref/hand_subcommand.rs (line 25)
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    fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error> {
        match matches.subcommand() {
            Some(("add", args)) => Ok(Self::Add(AddArgs::from_arg_matches(args)?)),
            Some(("remove", args)) => Ok(Self::Remove(RemoveArgs::from_arg_matches(args)?)),
            Some((_, _)) => Err(Error::raw(
                ErrorKind::UnrecognizedSubcommand,
                "Valid subcommands are `add` and `remove`",
            )),
            None => Err(Error::raw(
                ErrorKind::MissingSubcommand,
                "Valid subcommands are `add` and `remove`",
            )),
        }
    }
    fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error> {
        match matches.subcommand() {
            Some(("add", args)) => *self = Self::Add(AddArgs::from_arg_matches(args)?),
            Some(("remove", args)) => *self = Self::Remove(RemoveArgs::from_arg_matches(args)?),
            Some((_, _)) => {
                return Err(Error::raw(
                    ErrorKind::UnrecognizedSubcommand,
                    "Valid subcommands are `add` and `remove`",
                ))
            }
            None => (),
        };
        Ok(())
    }
examples/cargo-example.rs (line 15)
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fn main() {
    let cmd = clap::Command::new("cargo")
        .bin_name("cargo")
        .subcommand_required(true)
        .subcommand(
            clap::command!("example").arg(
                clap::arg!(--"manifest-path" <PATH>)
                    .required(false)
                    .value_parser(clap::value_parser!(std::path::PathBuf)),
            ),
        );
    let matches = cmd.get_matches();
    let matches = match matches.subcommand() {
        Some(("example", matches)) => matches,
        _ => unreachable!("clap should ensure we don't get here"),
    };
    let manifest_path = matches.get_one::<std::path::PathBuf>("manifest-path");
    println!("{:?}", manifest_path);
}
examples/repl.rs (line 34)
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fn respond(line: &str) -> Result<bool, String> {
    let args = shlex::split(line).ok_or("error: Invalid quoting")?;
    let matches = cli()
        .try_get_matches_from(&args)
        .map_err(|e| e.to_string())?;
    match matches.subcommand() {
        Some(("ping", _matches)) => {
            write!(std::io::stdout(), "Pong").map_err(|e| e.to_string())?;
            std::io::stdout().flush().map_err(|e| e.to_string())?;
        }
        Some(("quit", _matches)) => {
            write!(std::io::stdout(), "Exiting ...").map_err(|e| e.to_string())?;
            std::io::stdout().flush().map_err(|e| e.to_string())?;
            return Ok(true);
        }
        Some((name, _matches)) => unimplemented!("{}", name),
        None => unreachable!("subcommand required"),
    }

    Ok(false)
}
examples/multicall-busybox.rs (line 36)
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fn main() {
    let cmd = Command::new(env!("CARGO_CRATE_NAME"))
        .multicall(true)
        .subcommand(
            Command::new("busybox")
                .arg_required_else_help(true)
                .subcommand_value_name("APPLET")
                .subcommand_help_heading("APPLETS")
                .arg(
                    Arg::new("install")
                        .long("install")
                        .help("Install hardlinks for all subcommands in path")
                        .exclusive(true)
                        .takes_value(true)
                        .default_missing_value("/usr/local/bin")
                        .value_parser(value_parser!(PathBuf))
                        .use_value_delimiter(false),
                )
                .subcommands(applet_commands()),
        )
        .subcommands(applet_commands());

    let matches = cmd.get_matches();
    let mut subcommand = matches.subcommand();
    if let Some(("busybox", cmd)) = subcommand {
        if cmd.contains_id("install") {
            unimplemented!("Make hardlinks to the executable here");
        }
        subcommand = cmd.subcommand();
    }
    match subcommand {
        Some(("false", _)) => exit(1),
        Some(("true", _)) => exit(0),
        _ => unreachable!("parser should ensure only valid subcommand names are used"),
    }
}
examples/git.rs (line 50)
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fn main() {
    let matches = cli().get_matches();

    match matches.subcommand() {
        Some(("clone", sub_matches)) => {
            println!(
                "Cloning {}",
                sub_matches.get_one::<String>("REMOTE").expect("required")
            );
        }
        Some(("push", sub_matches)) => {
            println!(
                "Pushing to {}",
                sub_matches.get_one::<String>("REMOTE").expect("required")
            );
        }
        Some(("add", sub_matches)) => {
            let paths = sub_matches
                .get_many::<PathBuf>("PATH")
                .into_iter()
                .flatten()
                .collect::<Vec<_>>();
            println!("Adding {:?}", paths);
        }
        Some(("stash", sub_matches)) => {
            let stash_command = sub_matches.subcommand().unwrap_or(("push", sub_matches));
            match stash_command {
                ("apply", sub_matches) => {
                    let stash = sub_matches.get_one::<String>("STASH");
                    println!("Applying {:?}", stash);
                }
                ("pop", sub_matches) => {
                    let stash = sub_matches.get_one::<String>("STASH");
                    println!("Popping {:?}", stash);
                }
                ("push", sub_matches) => {
                    let message = sub_matches.get_one::<String>("message");
                    println!("Pushing {:?}", message);
                }
                (name, _) => {
                    unreachable!("Unsupported subcommand `{}`", name)
                }
            }
        }
        Some((ext, sub_matches)) => {
            let args = sub_matches
                .get_many::<OsString>("")
                .into_iter()
                .flatten()
                .collect::<Vec<_>>();
            println!("Calling out to {:?} with {:?}", ext, args);
        }
        _ => unreachable!(), // If all subcommands are defined above, anything else is unreachabe!()
    }

    // Continued program logic goes here...
}

Return the name and ArgMatches of the current subcommand.

Subcommand values are put in a child ArgMatches

Returns None if the subcommand wasn’t present at runtime,

Examples
 let mut app_m = Command::new("git")
     .subcommand(Command::new("clone"))
     .subcommand(Command::new("push"))
     .subcommand(Command::new("commit"))
     .subcommand_required(true)
     .get_matches();

let (name, sub_m) = app_m.remove_subcommand().expect("required");
match (name.as_str(), sub_m) {
    ("clone",  sub_m) => {}, // clone was used
    ("push",   sub_m) => {}, // push was used
    ("commit", sub_m) => {}, // commit was used
    (name, _)         => unimplemented!("{}", name),
}

Another useful scenario is when you want to support third party, or external, subcommands. In these cases you can’t know the subcommand name ahead of time, so use a variable instead with pattern matching!

// Assume there is an external subcommand named "subcmd"
let mut app_m = Command::new("myprog")
    .allow_external_subcommands(true)
    .get_matches_from(vec![
        "myprog", "subcmd", "--option", "value", "-fff", "--flag"
    ]);

// All trailing arguments will be stored under the subcommand's sub-matches using an empty
// string argument name
match app_m.remove_subcommand() {
    Some((external, mut sub_m)) => {
         let ext_args: Vec<String> = sub_m.remove_many("")
            .expect("`file`is required")
            .collect();
         assert_eq!(external, "subcmd");
         assert_eq!(ext_args, ["--option", "value", "-fff", "--flag"]);
    },
    _ => {},
}

The ArgMatches for the current subcommand.

Subcommand values are put in a child ArgMatches

Returns None if the subcommand wasn’t present at runtime,

Panics

If id is is not a valid subcommand.

Examples
let app_m = Command::new("myprog")
    .arg(Arg::new("debug")
        .short('d')
        .action(ArgAction::SetTrue)
    )
    .subcommand(Command::new("test")
        .arg(Arg::new("opt")
            .long("option")
            .takes_value(true)))
    .get_matches_from(vec![
        "myprog", "-d", "test", "--option", "val"
    ]);

// Both parent commands, and child subcommands can have arguments present at the same times
assert!(*app_m.get_one::<bool>("debug").expect("defaulted by clap"));

// Get the subcommand's ArgMatches instance
if let Some(sub_m) = app_m.subcommand_matches("test") {
    // Use the struct like normal
    assert_eq!(sub_m.get_one::<String>("opt").map(|s| s.as_str()), Some("val"));
}
Examples found in repository?
examples/tutorial_builder/01_quick.rs (line 54)
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fn main() {
    let matches = command!()
        .arg(arg!([name] "Optional name to operate on"))
        .arg(
            arg!(
                -c --config <FILE> "Sets a custom config file"
            )
            // We don't have syntax yet for optional options, so manually calling `required`
            .required(false)
            .value_parser(value_parser!(PathBuf)),
        )
        .arg(
            arg!(
                -d --debug "Turn debugging information on"
            )
            .action(ArgAction::Count),
        )
        .subcommand(
            Command::new("test")
                .about("does testing things")
                .arg(arg!(-l --list "lists test values").action(ArgAction::SetTrue)),
        )
        .get_matches();

    // You can check the value provided by positional arguments, or option arguments
    if let Some(name) = matches.get_one::<String>("name") {
        println!("Value for name: {}", name);
    }

    if let Some(config_path) = matches.get_one::<PathBuf>("config") {
        println!("Value for config: {}", config_path.display());
    }

    // You can see how many times a particular flag or argument occurred
    // Note, only flags can have multiple occurrences
    match matches
        .get_one::<u8>("debug")
        .expect("Count's are defaulted")
    {
        0 => println!("Debug mode is off"),
        1 => println!("Debug mode is kind of on"),
        2 => println!("Debug mode is on"),
        _ => println!("Don't be crazy"),
    }

    // You can check for the existence of subcommands, and if found use their
    // matches just as you would the top level cmd
    if let Some(matches) = matches.subcommand_matches("test") {
        // "$ myapp test" was run
        if *matches.get_one::<bool>("list").expect("defaulted by clap") {
            // "$ myapp test -l" was run
            println!("Printing testing lists...");
        } else {
            println!("Not printing testing lists...");
        }
    }

    // Continued program logic goes here...
}

The name of the current subcommand.

Returns None if the subcommand wasn’t present at runtime,

Examples
 let app_m = Command::new("git")
     .subcommand(Command::new("clone"))
     .subcommand(Command::new("push"))
     .subcommand(Command::new("commit"))
     .get_matches();

match app_m.subcommand_name() {
    Some("clone")  => {}, // clone was used
    Some("push")   => {}, // push was used
    Some("commit") => {}, // commit was used
    _              => {}, // Either no subcommand or one not tested for...
}
Examples found in repository?
examples/multicall-hostname.rs (line 12)
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fn main() {
    let cmd = Command::new(env!("CARGO_CRATE_NAME"))
        .multicall(true)
        .arg_required_else_help(true)
        .subcommand_value_name("APPLET")
        .subcommand_help_heading("APPLETS")
        .subcommand(Command::new("hostname").about("show hostname part of FQDN"))
        .subcommand(Command::new("dnsdomainname").about("show domain name part of FQDN"));

    match cmd.get_matches().subcommand_name() {
        Some("hostname") => println!("www"),
        Some("dnsdomainname") => println!("example.com"),
        _ => unreachable!("parser should ensure only valid subcommand names are used"),
    }
}

Non-panicking version of ArgMatches::get_one

Non-panicking version of ArgMatches::get_many

Non-panicking version of ArgMatches::get_raw

Non-panicking version of ArgMatches::remove_one

Non-panicking version of ArgMatches::remove_many

Non-panicking version of ArgMatches::contains_id

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Compare self to key and return true if they are equal.

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.