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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

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")

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")

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)

Sets a hidden alias for this argument value.

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

Sets multiple hidden aliases for this argument value.

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

Reflection

Get the name of the argument value

Get the help specified for this argument, if any

Deprecated, replaced with PossibleValue::is_hide_set

Report if PossibleValue::hide is set

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

Returns all valid values of the argument value.

Namely the name and all aliases.

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));

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

Converts to this type from the input type.

Converts to this type from the input type.

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

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

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.