Trait clap::ValueEnum

source · [−]

pub trait ValueEnum: Sized + Clone {
    fn value_variants<'a>() -> &'a [Self]ⓘNotable traits for &[u8]impl<'_> Read for &[u8]impl<'_> Write for &mut [u8];
    fn to_possible_value<'a>(&self) -> Option<PossibleValue<'a>>;

    fn from_str(input: &str, ignore_case: bool) -> Result<Self, String> { ... }
}

Expand description

Parse arguments into enums.

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

Call Arg::possible_values
Allowing using the #[clap(default_value_t)] attribute without implementing Display.

See the derive reference for attributes and best practices.

NOTE: Deriving requires the [derive feature flag][crate::_features]

Example

#[derive(clap::Parser)]
struct Args {
   #[clap(value_enum)]
   level: Level,
}

#[derive(clap::ValueEnum, Clone)]
enum Level {
   Debug,
   Info,
   Warning,
   Error,
}