Enum ParameterError 

#[non_exhaustive]
pub enum ParameterError<'arg> {
    NeedArgument,
    FlagGotArgument(&'arg Arg),
    GotAdditionalInstance,
    ParseError {
        arg: &'arg Arg,
        message: String,
    },
    ShouldBe {
        arg: &'arg Arg,
        expected: &'static [&'static str],
    },
    Custom {
        message: String,
    },
}

An error trying to parse a parameter from a --flag or positional argument. These error are produced from the primitive types, like bools and strings and vectors.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

NeedArgument

This parameter needs an argument and didn’t get one

FlagGotArgument(&'arg Arg)

This parameter is flag; it got an argument and didn’t want one

GotAdditionalInstance

This parameter appeared more than once or too many times

ParseError

Failed to parse the argument

Fields

arg: &'arg Arg

message: String

ShouldBe

The argument should have been one of these (or, possibly, a case insensitive variation)

Fields

arg: &'arg Arg

expected: &'static [&'static str]

Custom

Something else went wrong

Fields

message: String

Trait Implementations

impl<'arg> Clone for ParameterError<'arg>

fn clone(&self) -> ParameterError<'arg>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'arg> Debug for ParameterError<'arg>

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

Formats the value using the given formatter.

impl<'arg> Error<'arg> for ParameterError<'arg>

fn needs_arg() -> Self

The parameter requires an argument, and none was provided.

fn got_arg(argument: &'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 Arg) -> Self

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

fn parse_error(arg: &'arg str, message: 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 Arg, message: impl Display) -> Self

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

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

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

fn custom(message: impl Display) -> Self

Something else went wrong