App feels like an awkward name in the API

[epage]

Maintainer's notes

• The plan is to rename App to Command, including in other names like app_from_crate and AppSettings

---

clap version: master

Existing code:

use clap::{app_from_crate, arg, App, AppSettings};

fn main() {
    let matches = app_from_crate!()
        .global_setting(AppSettings::PropagateVersion)
        .global_setting(AppSettings::UseLongFormatForHelpSubcommand)
        .setting(AppSettings::SubcommandRequiredElseHelp)
        .subcommand(
            App::new("add")
                .about("Adds files to myapp")
                .arg(arg!([NAME])),
        )
        .get_matches();

    match matches.subcommand() {
        Some(("add", sub_matches)) => println!(
            "'myapp add' was used, name is: {:?}",
            sub_matches.value_of("NAME")
        ),
        _ => unreachable!(),
    }
}

Personally, its always felt weird constructing an "App" and then adding "apps" as subcommands.

[epage]

I've considered names like Parser or ParserBuilder (see #2911) but we run into conflicts between builder and derive traits.

When splitting up the impl blocks in the docs, I had the idea for Command. I think this makes more sense for the argument to Command::new, in subcommand context, etc.

See

use clap::{app_from_crate, arg, App, AppSettings};

fn main() {
    let matches = command_from_crate!()
        .global_setting(CommandSettings::PropagateVersion)
        .global_setting(CommandSettings::UseLongFormatForHelpSubcommand)
        .setting(CommandSettings::SubcommandRequiredElseHelp)
        .subcommand(
            Command::new("add")
                .about("Adds files to myapp")
                .arg(arg!([NAME])),
        )
        .get_matches();

    match matches.subcommand() {
        Some(("add", sub_matches)) => println!(
            "'myapp add' was used, name is: {:?}",
            sub_matches.value_of("NAME")
        ),
        _ => unreachable!(),
    }
}

[nicoburns]

Command seems right to me. That's what I've seen other CLI parsing libraries use for this concept. I suppose Subcommand could also work to match the method name. App definitely seems confusing to me. I would expect App to contain the core logic of my program not CLI argument parsing.

[epage]

We've now done

• App -> Command
• app_from_crate -> command
• IntoApp::into_app -> CommandFactory::command

The only thing left is removing the deprecations in 4.0. Since we have #3021 for that, going to close this out.