Trait `ValueEnum`

trait ValueEnum: Sized + Clone

Parse arguments into enums.

When deriving Parser, a field whose type implements ValueEnum can have the attribute #[arg(value_enum)] which will

Call [EnumValueParser][crate::builder::EnumValueParser]
Allowing using the #[arg(default_value_t)] attribute without implementing Display.

NOTE: Deriving requires the derive feature flag

Required Methods

fn value_variants<'a>() -> &'a [Self]

All possible argument values, in display order.

fn to_possible_value(self: &Self) -> Option<PossibleValue>

The canonical argument value.

The value is None for skipped variants.

fn from_str(input: &str, ignore_case: bool) -> Result<Self, String>: Parse an argument into Self.