Chapter 2 "echor": breaking changes in clap 3 & 4 need adjustment

[UweSauter]

For everyone trying to follow along using a current (4.2.7) version of clap here's a working solution:

use clap::{Arg, ArgAction, Command};

fn main() {
    let matches = Command::new("echor")
        .version("0.1.0")
        .author("author")
        .about("echo in Rust")
        .arg(
            Arg::new("text")
                .value_name("TEXT")
                .help("input text")
                .required(true)
                .action(ArgAction::Append),
        )
        .arg(
            Arg::new("omit newline")
                .short('n')
                .help("Don't print newline character")
                .action(ArgAction::SetTrue),
        )
        .get_matches();
    let text: Vec<&str> = matches
        .get_many("text")
        .unwrap()
        .map(String::as_str)
        .collect();
    let omit_newline = matches.get_flag("omit newline");
    let ending = if omit_newline { "" } else { "\n" };
    print!("{}{}", text.join(" "), ending);
}

There have been some breaking changes in clap since 2.33 that required some work to get right. Most challenging was to collect the arguments into text.