Do you find this syntax odd?

[0x7FFFFFFFFFFFFFFF]

I created a simple app.

Cargo.toml

[package]
name = "clap1"
version = "0.1.0"
edition = "2018"

[dependencies]
clap = "3.0.0-beta.5"

main.rs

use clap::{App, Arg, ArgGroup};

fn main() {
    let matches = App::new("Clap1")
        .version("0.1.0")
        .about(r#"Clap1 is a testing app for clap."#)

        .arg(Arg::new("read")
            .short('r')
            .long("read")
            .about("read something interesting")
            .takes_value(false))
        .arg(Arg::new("write")
            .short('w')
            .long("write")
            .about("write something interesting")
            .takes_value(false))
        .arg(Arg::new("read_or_write_or_test")
            .short('t')
            .long("read_or_write_or_test")
            .about("read_or_write_or_test something interesting")
            .takes_value(false))

        .group(ArgGroup::new("g1").args(&["read", "write"]).multiple(false))
        .group(ArgGroup::new("g2").args(&["read", "write", "read_or_write_or_test"]).multiple(true).required(true))
        .get_matches();
}

When I run it with --help, I got this:

The <--read part looks a little bit weird to me. It's like an arrow pointing to something. What do you guys think of it? As I remember, many command utilities use {...} to denote a required parameter. For example, on this IBM document page, it says:

{ }
Delimits a set of mutually exclusive arguments when one of the arguments is required. If the arguments are optional, they are enclosed in brackets ([ ]).

wrb -import {rule_pack | rule_set}...
In this example, the -l and -f format arguments are mutually exclusive and optional. The profile argument is required. The key argument is optional. The ellipsis (...) that follows the key argument indicates that you can specify multiple key names.

Any ideas? Thanks.

[0x7FFFFFFFFFFFFFFF]

This Microsoft document page also states that they use {...} to denote required parameter.

[epage]

docopt uses (...) for required groups, see http://docopt.org/

[epage]

Note that our usage parser also uses <. We'd want to have the two match and we'd probably want to help people transition.

See https://docs.rs/clap/2.33.3/clap/struct.Arg.html#impl-From%3C%26%27help%20str%3E

[pksunkara]

Do we want to create a new issue to look at our usage strings for 4.0?

[epage]

Sure, created #2951. I didn't target it for 4.0 because I'm wanting to be cautious of overcommitting :)

A contributor might be able to develop this behind a feature flag which would decouple it from a specific breaking release and allow it to just catch the next available one.

[0x7FFFFFFFFFFFFFFF]

Oracle also uses {} to denote required stuff. See here.

Convention	Meaning	Example
{ }	Braces enclose two or more items, one of which is required. Do not enter the braces.	{ENABLE | DISABLE}