Allow command options to be added externally

[timriley]

In hanami-cli we have generator commands like generate action.

Then in hanami-rspec and hanami-minitest, we add hooks to those commands, like this:

Hanami::CLI.after "generate action", Commands::Generate::Action

Those hooks want a specific extra option for them to do their job, in this case --skip-tests.

Right now the only way to support this extra option is to declare it on the base command in hanami-cli, even though nothing inside that project needs that option.

It would be nice if we could find a way for extra options to be added externally, so projects like hanami-rspec can add them specifically for their own extensions, and the base command can remain unchanged.

[afomera]

I'm putting my hand up for this one @timriley!

Gonna take a go at this one, but if anyone else had their eye on it too, thats ok too!

[afomera]

Initially I'm thinking something like:

# hanami-rspec - the flag now lives next to the hook that consumes it
Hanami::CLI.after  "generate action", Commands::Generate::Action
Hanami::CLI.option "generate action", :skip_tests,
                   type: :flag, default: false, desc: "Skip test generation"

Hanami::CLI.argument "generate action", :suite, required: false, values: %w[rspec minitest]

Could be good to meet this goal. I had considered briefly about .description or something for adding and extending help descriptions, but I think we can add that in down the road vs overriding the description etc.

Then we can drop that flag out of the hanami cli class

This does require two things to be true:

the base command's #call must accept ** (already the dry-cli idiom); and external arguments should be required: false, largely due to how the Parser parses and sorts things

[timriley]

@afomera I think that API looks good to me! Putting it on the registry and having it feel the same as adding the hooks makes a lot of sense.

Related thoughts:

• It might be good to add a Registry#command method that returns the command class itself (as an escape hatch to allow any other modifications that might be needed). Registry#option could then just become a thin wrapper around that.
• We should make it so that it's safe and fine for same option to be added multiple times (imagine e.g. an app that for some reason had hanami-rspec and hanami-minitest bundled, where both of them add the --skip-tests option).
  • This should be allowed only while the option has the same :type, :required, :values and :default options. If a duplicate option is added with differing values, that will lead to unexpected behaviour, and should raise an exception.
  • For the above, I think we should ignore the :cast option since procs aren't comparable, so we just have to check those options that actually are.
• I wonder if we can avoid the need for the base command #call method to accept **. Having base command be aware of possible third party extensions via ** feels like just another (although still slightly better) variation of our generator commands having to add the skip_tests: args. What if instead we modified the command dispatcher in CLI itself to check for the args that each command and hook receive, and only pass only the args that match? This way our base classes could only care about their own args, and our hooks wouldn't need to add ** either.

Let me know what you think! Would definitely love your help getting this built :)

[afomera]

@timriley I think that sounds all good to me! I have enough here to get going and we can flesh it out with some code in-front of us I think! The call-out to make sure it's safe if the same option is added multiple times was a great catch.