Module clap::_derive::_tutorial::chapter_1

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Available on crate feature unstable-doc only.
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§Configuring the Parser

You use derive Parser to start building a parser.

use clap::Parser;

#[derive(Parser)]
#[command(name = "MyApp")]
#[command(version = "1.0")]
#[command(about = "Does awesome things", long_about = None)]
struct Cli {
    #[arg(long)]
    two: String,
    #[arg(long)]
    one: String,
}

fn main() {
    let cli = Cli::parse();

    println!("two: {:?}", cli.two);
    println!("one: {:?}", cli.one);
}
$ 02_apps_derive --help
Does awesome things

Usage: 02_apps_derive[EXE] --two <TWO> --one <ONE>

Options:
      --two <TWO>  
      --one <ONE>  
  -h, --help       Print help
  -V, --version    Print version

$ 02_apps_derive --version
MyApp 1.0

You can use #[command(version, about)] attribute defaults on the struct to fill these fields in from your Cargo.toml file.

use clap::Parser;

#[derive(Parser)]
#[command(version, about, long_about = None)] // Read from `Cargo.toml`
struct Cli {
    #[arg(long)]
    two: String,
    #[arg(long)]
    one: String,
}

fn main() {
    let cli = Cli::parse();

    println!("two: {:?}", cli.two);
    println!("one: {:?}", cli.one);
}
$ 02_crate_derive --help
A simple to use, efficient, and full-featured Command Line Argument Parser

Usage: 02_crate_derive[EXE] --two <TWO> --one <ONE>

Options:
      --two <TWO>  
      --one <ONE>  
  -h, --help       Print help
  -V, --version    Print version

$ 02_crate_derive --version
clap [..]

You can use #[command] attributes on the struct to change the application level behavior of clap. Any Command builder function can be used as an attribute, like Command::next_line_help.

use clap::Parser;

#[derive(Parser)]
#[command(version, about, long_about = None)]
#[command(next_line_help = true)]
struct Cli {
    #[arg(long)]
    two: String,
    #[arg(long)]
    one: String,
}

fn main() {
    let cli = Cli::parse();

    println!("two: {:?}", cli.two);
    println!("one: {:?}", cli.one);
}
$ 02_app_settings_derive --help
A simple to use, efficient, and full-featured Command Line Argument Parser

Usage: 02_app_settings_derive[EXE] --two <TWO> --one <ONE>

Options:
      --two <TWO>
          
      --one <ONE>
          
  -h, --help
          Print help
  -V, --version
          Print version

Re-exports§