cargo::util::command_prelude

# Macro value_parser

    macro_rules! value_parser {
        ($name:ty) => { ... };
    }

Expand description

Select a [`ValueParser`] implementation from the intended type

Supported types

- [`ValueParserFactory` types][ValueParserFactory], including
  - [Native types][ValueParser]: `bool`, `String`, `OsString`, `PathBuf`
  - [Ranged numeric types][RangedI64ValueParser]: `u8`, `i8`, `u16`, `i16`, `u32`, `i32`, `u64`, `i64`
- [`ValueEnum` types][crate::ValueEnum]
- `From<OsString>` types and `From<&OsStr>` types
- `From<String>` types and `From<&str>` types
- `FromStr` types, including usize, isize

## §Example

Usage:

    let mut cmd = clap::Command::new("raw")
        .arg(
            clap::Arg::new("output")
                .value_parser(clap::value_parser!(PathBuf))
                .required(true)
        );

    let m = cmd.try_get_matches_from_mut(["cmd", "file.txt"]).unwrap();
    let port: &PathBuf = m.get_one("output")
        .expect("required");
    assert_eq!(port, Path::new("file.txt"));

Example mappings:

    // Built-in types
    let parser = clap::value_parser!(String);
    assert_eq!(format!("{parser:?}"), "ValueParser::string");
    let parser = clap::value_parser!(std::ffi::OsString);
    assert_eq!(format!("{parser:?}"), "ValueParser::os_string");
    let parser = clap::value_parser!(std::path::PathBuf);
    assert_eq!(format!("{parser:?}"), "ValueParser::path_buf");
    clap::value_parser!(u16).range(3000..);
    clap::value_parser!(u64).range(3000..);

    // FromStr types
    let parser = clap::value_parser!(usize);
    assert_eq!(format!("{parser:?}"), "_AnonymousValueParser(ValueParser::other(usize))");

    // ValueEnum types
    clap::value_parser!(ColorChoice);