rust - 有没有办法让 clap treat -？和-h一样吗？

Question

clap crate 为 -h 选项实现了内置行为，但它似乎没有为 -? 做同样的事情。有没有办法告诉它这样做？

Answer 1

我在 clap repository 上开了一个问题.作者/主要贡献者已在那里回答。这是代码的副本，它回答了这个问题:

extern crate clap;

use std::env;
use std::process;

use clap::{App, Arg};

fn main() {
    // We build the App instance and save it, so we can
    // use it later if needed
    let mut app = App::new("prog").arg(
        Arg::with_name("help")
            .short("?")
            .help("Also prints the help message"),
    );

    // We call this method which will do all the
    //parsing, but not consume our App instance
    let res = app.get_matches_from_safe_borrow(env::args_os());

    // This calls all the normal clap error messages
    // if one should exist
    let matches = res.unwrap_or_else(|e| e.exit());

    // Now we check for ?
    if matches.is_present("help") {
        let _ = app.print_help();
        println!(""); // adds a newline
        process::exit(0);
    }

    // Now we can use matches like normal...
}