Module clap::_cookbook::cargo_example

Available on crate feature unstable-doc only.

Example: cargo subcommand (Builder API)

fn main() {
    let cmd = clap::Command::new("cargo")
        .bin_name("cargo")
        .subcommand_required(true)
        .subcommand(
            clap::command!("example").arg(
                clap::arg!(--"manifest-path" <PATH>)
                    .value_parser(clap::value_parser!(std::path::PathBuf)),
            ),
        );
    let matches = cmd.get_matches();
    let matches = match matches.subcommand() {
        Some(("example", matches)) => matches,
        _ => unreachable!("clap should ensure we don't get here"),
    };
    let manifest_path = matches.get_one::<std::path::PathBuf>("manifest-path");
    println!("{manifest_path:?}");
}

For more on creating a custom subcommand, see the cargo book. The crate clap-cargo can help in mimicking cargo’s interface.

The help looks like:

$ cargo-example --help
Usage: cargo <COMMAND>

Commands:
  example  A simple to use, efficient, and full-featured Command Line Argument Parser
  help     Print this message or the help of the given subcommand(s)

Options:
  -h, --help  Print help

$ cargo-example example --help
A simple to use, efficient, and full-featured Command Line Argument Parser

Usage: cargo example [OPTIONS]

Options:
      --manifest-path <PATH>  
  -h, --help                  Print help
  -V, --version               Print version

Then to directly invoke the command, run:

$ cargo-example example
None

$ cargo-example example --manifest-path Cargo.toml
Some("Cargo.toml")