Module clap::_cookbook::cargo_example_derive

Available on crate feature unstable-doc only.

Example: cargo subcommand (Derive API)

use clap::Parser;

#[derive(Parser)] // requires `derive` feature
#[clap(name = "cargo")]
#[clap(bin_name = "cargo")]
enum Cargo {
    ExampleDerive(ExampleDerive),
}

#[derive(clap::Args)]
#[clap(author, version, about, long_about = None)]
struct ExampleDerive {
    #[clap(long, value_parser)]
    manifest_path: Option<std::path::PathBuf>,
}

fn main() {
    let Cargo::ExampleDerive(args) = Cargo::parse();
    println!("{:?}", args.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-derive --help
cargo 

USAGE:
    cargo <SUBCOMMAND>

OPTIONS:
    -h, --help    Print help information

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

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

USAGE:
    cargo example-derive [OPTIONS]

OPTIONS:
    -h, --help                             Print help information
        --manifest-path <MANIFEST_PATH>    
    -V, --version                          Print version information

Then to directly invoke the command, run:

$ cargo-example-derive example-derive
None

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