Perform help formatting/rendering for arg.help(...), just like doc comments in clap-derive

[stevenengler]

Clap derive performs some formatting/rendering of doc comments when displaying them as help text, but this same process does not occur for strings passed to arg.help(...).

use clap::Parser;

#[derive(Parser)]
struct Cli {
    /// Hello
    /// world.
    foo: Option<String>,
    
    #[arg(help = "Hello\nworld.")]
    bar: Option<String>,
}

fn main() {
    Cli::parse_from(["foo", "--help"]);
}

Usage: foo [FOO] [BAR]

Arguments:
  [FOO]  Hello world
  [BAR]  Hello
         world.

Options:
  -h, --help  Print help

Is there any existing option to perform the same formatting with arg.help(...)? Or could StyledStr be extended to support this?

[epage]

This is derive specific logic for transforming a markdown doc comment to arg.help and arg.long_help. We have issues about how incomplete the markdown support is. I see it unlikely to try to integrate all of that into the builder API though we might offer a parallel API for it. We'll have to see how that logic evolves and is unlikely to be a goal on its own.

You can manually specify #[arg(help)] and #[arg(long_help)] though it requires duplicating the first section. On the other hand, it lets you customize things for each specific scenario.

[stevenengler]

Okay thanks!