Struct EmptyError 

pub struct EmptyError;

A simple argument parsing error type that contains no data. Mostly used for testing and code examples.

Trait Implementations

impl Clone for EmptyError

fn clone(&self) -> EmptyError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EmptyError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for EmptyError

fn default() -> EmptyError

Returns the “default value” for a type.

impl Display for EmptyError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'arg> Error<'arg> for EmptyError

fn needs_arg() -> Self

The parameter requires an argument, and none was provided.

fn got_arg(_: &'arg Arg) -> Self

The parameter is a --switch; it must NOT have a value, and got one.

fn got_additional_instance() -> Self

The argument appeared more times than expected (usually more than once) on the command line

fn invalid_utf8(_: &'arg Arg) -> Self

The argument wasn’t valid UTF-8 and should be.

fn parse_error(_: &str, _: impl Display) -> Self

The argument was valid UTF-8, but it failed to parse into an instance of the type.

fn byte_parse_error(_: &'arg Arg, _: impl Display) -> Self

The argument failed to parse into an instance of the type.

fn should_be(_: &'arg Arg, _: &'static [&'static str]) -> Self

The argument should be one of the given values (or, possibly, a case insensitive variation)

fn custom(_: impl Display) -> Self

Something else went wrong

impl<'arg> Error<'arg> for EmptyError

type StateError<A> = EmptyError

fn positional(_: &'arg Arg, _: Self) -> Self

There was an error handling a positional argument

fn long_with_argument(_: &'arg Arg, _: &'arg Arg, _: Self) -> Self

There was an error handling a --long=argument argument

fn long<A>(_: &'arg Arg, _: Self) -> Self

There was an error handling a --long long argument

fn short<A>(_: u8, _: Self) -> Self

There was an error handling a -s short argument

fn and(self, _: Self) -> Self

There were multiple argument errors

impl<'arg, A> Error<'arg, A> for EmptyError

type ParameterError = EmptyError

Error type for parameter errors (see parameter).

type FlagList = EmptyError

List of flags for conflicts_with_flags.

fn parameter(_: &'static str, _: Self::ParameterError) -> Self

A parameter type returned an error. This means that the argument was recognized and matched to a specific field, but something went wrong during parsing, such as a letter appearing in a numeric parameter.

fn unrecognized(_: A) -> Self

An argument was unrecognized. In this case, the Argument can be returned unused inside of Self, so that it can be retried by a different parser. For instance, a subcommand parser could indicate that an argument is unrecognized, and that argument can later be handled as a global argument.

fn flattened(_: &'static str, _: Self) -> Self

There was a state error from another State inside of this one.

fn unknown_subcommand(_: &'static [&'static str]) -> Self

The positional argument was interpreted as a subcommand, but wasn’t recognized as a known subcommand. The list of known subcommands is given.

fn wrong_subcommand_for_argument(_: &str, _: &[&'static str]) -> Self

The option was recognized, but it isn’t a valid for this particular subcommand. The current subcommand, along with the list of subcommands that accept this option, are given

fn conflicts_with_flags(_flags: Self::FlagList) -> Self

The argument conflicts with the given flags that were already parsed.

fn help_requested(_: HelpRequest) -> Self

This was a request for a usage message. This error doesn’t need to interrupt argument parsing, since it can be useful to have a complete state object to print more contextually useful usage messages.

impl Error for EmptyError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl Error for EmptyError

type FlagList = EmptyError

When reporting any_required_flag, we need to be able to report a list of flags. This type allows the error to define the container it wants to use for those flags.

fn required_flag(_: &'static str, _: Tags<'static>, _: &'static str) -> Self

A required flag wasn’t present.

fn required_positional(_: &'static str, _: &'static str) -> Self

A required positional field wasn’t present.

fn any_required_flag(_: Self::FlagList) -> Self

At least one of the flags in this list were required.

fn flattened(_: &'static str, _: Self) -> Self

There was an error building a flattened field.

fn required_subcommand(_: &'static [&'static str]) -> Self

We required a subcommand, but none was provided.

fn custom(_: impl Display) -> Self

Something else went wrong.

impl<'a> FlagsList<'a> for EmptyError

fn new(_: Tags<'a>, _: &'a str) -> Self

Create a new FlagsList. Flags lists are guaranteed to include at least one flag, so this constructor includes that flag.

fn add(&mut self, _: Tags<'a>, _: &'a str)

Insert an additional flag into this set.

impl Copy for EmptyError