Support root commands that doesn't implement call

[gustavothecoder]

Resolve #96

I would like to add descriptions to my root commands without implementing a proper command, like a namespace.

Example

Command

class Namespace < Dry::CLI::Namespace
  desc "This is a namespace"

  class MyCommand < Dry::CLI::Command
    desc "I'm a concrete command"

    def call(**params)
      puts "I'm a concrete command"
    end
  end
end

Result

[benoittgt]

Isn't bizarre to have a "command" that the uniq usage is to print top level usage? I am wondering if it should be a better idea to move the usage of top class as specific dsl. Like suggested here #96 ?

[gustavothecoder]

It is. I tried to implement the suggestion from #96, but I couldn't figure out how to do it. Maybe we can create the Dry::CLI::Namespace class, so It will look less strange.

[benoittgt]

That's a good idea.

[timriley]

@gustavothecoder I like the idea of this being a specialised Namespace class. That way, when the class is used, it will be clearer that its purpose is to provide information about a grouping of subcommands only, and not its own distinct command behaviour.

I prefer this help text residing in a concrete class instead of being part of the top-level command registration API, since that feels more consistent with how the rest of the CLI construction is done: a class for each thing.

If you're still interested in working on this PR, I'd love it if you could make this adjustment! Let me know what you think.

[gustavothecoder]

@timriley Done! I think it looks better using the Namespace class.

[benoittgt]

This is a great proposal. I would love to be able to use this in our CLI.