foropts-rs: iterator-style option parsing for Rust

Most argument parsing libraries, such as clap, treat the arguments as a multimap; foropts treats the arguments as a sequence. This usually isn’t what you want, but occasionally it is.

Usage

It's on crates.io, so you can add

[dependencies]
foropts = "0.3.6"

to your Cargo.toml and

extern crate foropts;

to your crate root.

This crate supports Rust version 1.22 and later.

Example

In this example, we accept one boolean flag, -v (or --verbose), and two string options, -b (or --before) and -a (or --after). The string options build a string, where the relative order of the appearances of -a and -b matters. This is hard to do when your arguments are treated as a multimap, but easy when you can iterate over them sequentially.

use foropts;

enum Opt {
    Before(String),
    After(String),
    Verbose,
}

let config =
    foropts::Config::new("build_string_example")
        .arg(foropts::Arg::parsed_param("BEFORE", Opt::Before)
             .short('b').long("before"))
        .arg(foropts::Arg::parsed_param("AFTER", Opt::After)
             .short('a').long("after"))
        .arg(foropts::Arg::flag(|| Opt::Verbose)
             .short('v').long("verbose"));

let mut verbose     = false;
let mut accumulator = String::new();

let opts = ["-b1", "-va", "2", "--after=3", "--before", "4"]
    .iter().map(ToString::to_string);

for opt in config.iter(opts) {
    match opt.unwrap_or_else(|e| config.exit_error(&e)) {
        Opt::Before(s) => accumulator = s + &accumulator,
        Opt::After(s)  => accumulator = accumulator + &s,
        Opt::Verbose   => verbose = true,
    }
}

assert_eq!( "4123", accumulator );
assert!( verbose );