# Struct clap::builder::PossibleValuesParser

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    pub struct PossibleValuesParser(_);

Expand description

Verify the value is from an enumerated set of `PossibleValue`.

See also:

- `EnumValueParser` for directly supporting `ValueEnum` types
- `TypedValueParser::map` for adapting values to a more specialized type, like an external enums that can’t implement `ValueEnum`

## Example

Usage:

    let mut cmd = clap::Command::new("raw")
        .arg(
            clap::Arg::new("color")
                .value_parser(clap::builder::PossibleValuesParser::new(["always", "auto", "never"]))
                .required(true)
        );

    let m = cmd.try_get_matches_from_mut(["cmd", "always"]).unwrap();
    let port: &String = m.get_one("color")
        .expect("required");
    assert_eq!(port, "always");

Semantics:

    let value_parser = clap::builder::PossibleValuesParser::new(["always", "auto", "never"]);
    assert!(value_parser.parse_ref(&cmd, arg, OsStr::new("random")).is_err());
    assert!(value_parser.parse_ref(&cmd, arg, OsStr::new("")).is_err());
    assert_eq!(value_parser.parse_ref(&cmd, arg, OsStr::new("always")).unwrap(), "always");
    assert_eq!(value_parser.parse_ref(&cmd, arg, OsStr::new("auto")).unwrap(), "auto");
    assert_eq!(value_parser.parse_ref(&cmd, arg, OsStr::new("never")).unwrap(), "never");

## Implementations

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### impl PossibleValuesParser

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#### pub fn new(values: impl Into<PossibleValuesParser>) -> Self

Verify the value is from an enumerated set pf `PossibleValue`.

## Trait Implementations

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### impl Clone for PossibleValuesParser

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#### fn clone(&self) -> PossibleValuesParser

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from `source`. Read more

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### impl Debug for PossibleValuesParser

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

Formats the value using the given formatter. Read more

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### impl<I, T> From<I> for PossibleValuesParser where
I: IntoIterator<Item = T>,
T: Into<PossibleValue>,

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#### fn from(values: I) -> Self

Converts to this type from the input type.

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### impl TypedValueParser for PossibleValuesParser

#### type Value = String

Argument’s value type

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#### fn parse_ref(
&self,
cmd: &Command,
arg: Option<&Arg>,
value: &OsStr
) -> Result<Self::Value, Error>

Parse the argument value Read more

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#### fn parse(
&self,
cmd: &Command,
arg: Option<&Arg>,
value: OsString
) -> Result<String, Error>

Parse the argument value Read more

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#### fn possible_values(
&self
) -> Option<Box<dyn Iterator<Item = PossibleValue> + '_>>

Reflect on enumerated value properties Read more

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#### fn map<T, F>(self, func: F) -> MapValueParser<Self, F> where
T: Send + Sync + Clone,
F: Fn(Self::Value) -> T + Clone,

Adapt a `TypedValueParser` from one value to another Read more

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#### fn try_map<T, E, F>(self, func: F) -> TryMapValueParser<Self, F> where
F: Fn(Self::Value) -> Result<T, E> + Clone + Send + Sync + 'static,
T: Send + Sync + Clone,
E: Into<Box<dyn Error + Send + Sync + 'static>>,

Adapt a `TypedValueParser` from one value to another Read more

## Auto Trait Implementations

### impl RefUnwindSafe for PossibleValuesParser

### impl Send for PossibleValuesParser

### impl Sync for PossibleValuesParser

### impl Unpin for PossibleValuesParser

### impl UnwindSafe for PossibleValuesParser

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T where
U: From<T>,

const: unstable · source

#### fn into(self) -> U

Calls `U::from(self)`.

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

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### impl<T> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### fn to_owned(&self) -> T

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

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#### fn clone_into(&self, target: &mut T)

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

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.