clap (Rust)

clap_usage generates a usage spec from a CLI built with clap.

Installation

[dependencies]
clap_usage = "2"

Quick Start

use clap::Command;

let mut cmd = Command::new("mycli")
    .version("1.0")
    .arg(clap::Arg::new("input"));

let mut buf = Vec::new();
clap_usage::generate(&mut cmd, "mycli", &mut buf);
println!("{}", String::from_utf8(buf).unwrap());

Integration Pattern

A common approach is to add a hidden --usage-spec flag that outputs the spec:

use clap::{Arg, Command};
use std::io;

let mut cmd = Command::new("mycli")
    .arg(Arg::new("usage-spec")
        .long("usage-spec")
        .hide(true)
        .action(clap::ArgAction::SetTrue));

let matches = cmd.clone().get_matches();

if matches.get_flag("usage-spec") {
    clap_usage::generate(&mut cmd, "mycli", &mut io::stdout());
    return;
}

Then pipe the output to usage:

mycli --usage-spec | usage generate completion bash
mycli --usage-spec | usage generate md --out-file docs.md
mycli --usage-spec | usage generate manpage --out-file mycli.1

Links

• crate on crates.io
• source code