Example use of a subcommand dispatcher for the Clap argument parser

command_map_example.rs

use std::error::Error;
use clap::{Arg, ArgMatches, builder::NonEmptyStringValueParser, Command};
use mysteriouspants_clap_action_command::{
    ActionCommand, CommandMap, get_one, vec1::{Vec1, vec1}
};

static NAME_ARG: &str = "name";

struct HelloWorldCommand {}

impl ActionCommand for HelloWorldCommand {
    fn name(&self) -> &'static str {
        "hello-world"
    }

    fn command(&self, command: Command) -> Command {
        command
            .about("Say hello to the world")
            .alias("h")
            .arg(
                Arg::new(NAME_ARG)
                    .short('n')
                    .value_name("NAME")
                    .required(false)
                    .value_parser(NonEmptyStringValueParser::new())
            )
    }

    fn action(
            &self, matches: Vec1<&ArgMatches>
    ) -> Result<(), Box<dyn Error>> {
        if let Some(name) = get_one::<String>(&matches, NAME_ARG) {
            println!("Hello, {}!", name);
        } else {
            println!("Hello, world!");
        }

        Ok(())
    }
}

let command_map = CommandMap::builder()
    .push(HelloWorldCommand {})
    // adding a new subcommand is as easy as referencing it here
    .build();
let command = Command::new("my-program").subcommands(command_map.commands());
let matches = command.get_matches_from([
    "my-program", "hello-world", "-n", "Steeve"
]);
command_map.dispatch(vec1![&matches]);