Structopt: Argument groups

[jackjen]

Is there a plan to add argument groups / mutually exclusive flags and or options? After a little searching I either couldn't see how to achieve them, or came to the conclusion that I would need to use clap directly.

For example,

Allow:
command --arg1
command --arg2
command --arg1 [name]

But not allow:
command --arg1 [name] --arg2

Also to combine the mutually exclusiveness these with subcommands,

Allow:
command subcommand --subarg1

But not allow:
command --arg1 subcommand --subarg1
command --arg1 [name] --arg2 subcommand --subarg1

(edit, added examples)

Thanks.

[TeXitoi]

Transcription of https://docs.rs/clap/2.26.0/clap/struct.Arg.html#method.conflicts_with

extern crate structopt;
#[macro_use]
extern crate structopt_derive;

use structopt::StructOpt;

#[derive(StructOpt, Debug)]
struct Opt {
    #[structopt(long = "config", conflicts_with = "debug")]
    cfg: Option<String>,
    #[structopt(long = "debug")]
    debug: bool,
}

fn main() {
    let opt = Opt::from_args();
    println!("{:?}", opt);
}

cargo run -- --debug --config file.conf
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `/home/gupinot/dev/test-rs/target/debug/test-rs --debug --config file.conf`
error: The argument '--config <cfg>' cannot be used with '--debug'

USAGE:
    test-rs --debug

For more information try --help

From the doc at https://docs.rs/structopt-derive/0.1.0/structopt_derive/

As with the struct attributes, every method of clap::Arg in the form of fn function_name(self, &str) can be used through specifying it as an attribute.

Does it answer your question? Do you have an idea of what we can do to help find this information?

[jackjen]

It does answer my question for the most part - my bad for not reading thoroughly. As for clarity, I think it's clear enough.

So I have the ability to specify conflicting arguments per app/subcommand.
What about conflicts with for a subcommand? (require the inability to specify a particular argument and a subcommand)

[TeXitoi]

I can't find the feature in clap. Do you know how to do that with clap? If that's not possible with clap, that's not possible with structopt.

[kpcyrd]

Close, but not exactly the same issue: Can I require that exactly one argument of two conflicting arguments is provided?

This is possible in clap by making the argument group required: https://kbknapp.github.io/clap-rs/clap/struct.ArgGroup.html

[TeXitoi]

https://github.com/TeXitoi/structopt/blob/master/examples/group.rs

[Fuuzetsu]

https://github.com/TeXitoi/structopt/blob/master/examples/group.rs

This is unsatisfactory as it doesn't allow for convenient parsing of enums. To quote the given example:

struct Opt {
    /// Set a custom HTTP verb
    #[structopt(long, group = "verb")]
    method: Option<String>,
    /// HTTP GET
    #[structopt(long, group = "verb")]
    get: bool,
    /// HTTP HEAD
    #[structopt(long, group = "verb")]
    head: bool,
    /// HTTP POST
    #[structopt(long, group = "verb")]
    post: bool,
    /// HTTP PUT
    #[structopt(long, group = "verb")]
    put: bool,
    /// HTTP DELETE
    #[structopt(long, group = "verb")]
    delete: bool,
}

To get something like

enum Method {
  Get,
  Head,
  Post,
  Put,
  Delete,
}

The user has to do something like

if opts.get { return Method::Get }
if opts.head { return Method::Post }
…
panic!("shouldn't happen or structopt failed to ensure some option was set");

which gets really annoying super fast.

[TeXitoi]

A more appropriate pattern for this use case is https://github.com/TeXitoi/structopt/blob/master/examples/enum_in_args.rs but that's a different interface.