Struct clap::PossibleValue

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pub struct PossibleValue<'help> { /* private fields */ }

Expand description

A possible value of an argument.

This is used for specifying possible values of Args.

NOTE: This struct is likely not needed for most usecases as it is only required to hide single values from help messages and shell completions or to attach help to possible values.

Examples

let cfg = Arg::new("config")
    .takes_value(true)
    .value_name("FILE")
    .value_parser([
        PossibleValue::new("fast"),
        PossibleValue::new("slow").help("slower than fast"),
        PossibleValue::new("secret speed").hide(true)
    ]);

Implementations

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impl<'help> PossibleValue<'help>

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pub fn new(name: &'help str) -> Self

Create a PossibleValue with its name.

The name will be used to decide whether this value was provided by the user to an argument.

NOTE: In case it is not hidden it will also be shown in help messages for arguments that use it as a possible value and have not hidden them through Arg::hide_possible_values(true).

Examples

PossibleValue::new("fast")

Examples found in repository ?

examples/tutorial_builder/04_01_enum.rs (line 17)

≺ ≻

    fn to_possible_value<'a>(&self) -> Option<PossibleValue<'a>> {
        Some(match self {
            Mode::Fast => PossibleValue::new("fast"),
            Mode::Slow => PossibleValue::new("slow"),
        })
    }

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pub fn help(self, help: &'help str) -> Self

Sets the help description of the value.

This is typically displayed in completions (where supported) and should be a short, one-line description.

Examples

PossibleValue::new("slow")
    .help("not fast")

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

Hides this value from help and shell completions.

This is an alternative to hiding through Arg::hide_possible_values(true), if you only want to hide some values.

Examples

PossibleValue::new("secret")
    .hide(true)

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pub fn alias(self, name: &'help str) -> Self

Sets a hidden alias for this argument value.

Examples

PossibleValue::new("slow")
    .alias("not-fast")

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pub fn aliases(self, names: I) -> Selfwhere
I: IntoIterator<Item = &'help str>,

Sets multiple hidden aliases for this argument value.

Examples

PossibleValue::new("slow")
    .aliases(["not-fast", "snake-like"])

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impl<'help> PossibleValue<'help>

Reflection

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pub fn get_name(&self) -> &'help str

Get the name of the argument value

Examples found in repository ?

examples/tutorial_builder/04_01_enum.rs (line 27)

    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.to_possible_value()
            .expect("no values are skipped")
            .get_name()
            .fmt(f)
    }

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pub fn get_help(&self) -> Option<&'help str>

Get the help specified for this argument, if any

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pub fn is_hidden(&self) -> bool

Deprecated, replaced with PossibleValue::is_hide_set

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pub fn is_hide_set(&self) -> bool

Report if PossibleValue::hide is set

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pub fn get_visible_name(&self) -> Option<&'help str>

Get the name if argument value is not hidden, None otherwise

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pub fn get_name_and_aliases(&self) -> impl Iterator<Item = &'help str> + '_

Returns all valid values of the argument value.

Namely the name and all aliases.

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pub fn matches(&self, value: &str, ignore_case: bool) -> bool

Tests if the value is valid for this argument value

The value is valid if it is either the name or one of the aliases.

Examples

let arg_value = PossibleValue::new("fast").alias("not-slow");

assert!(arg_value.matches("fast", false));
assert!(arg_value.matches("not-slow", false));

assert!(arg_value.matches("FAST", true));
assert!(!arg_value.matches("FAST", false));

Examples found in repository ?

examples/tutorial_builder/04_01_enum.rs (line 37)

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        for variant in Self::value_variants() {
            if variant.to_possible_value().unwrap().matches(s, false) {
                return Ok(*variant);
            }
        }
        Err(format!("Invalid variant: {}", s))
    }