Optional and required flags are swapped in the "Usage" message

[Mirandatz]

Running python script.py command

import fire


class Example:

    def command(self, *, arg1: bool, arg2: bool = True, arg3: bool = False):
        pass


if __name__ == '__main__':
    fire.Fire(Example)

Prints

ERROR: Missing required flags: {'arg1'}
Usage: download.py command <flags>
  optional flags:        --arg1
  required flags:        --arg2 | --arg3

The "ERROR" message correctly points that arg1 is required, but the "Usage" message is swapping required and optional arguments.

[dbieber]

Thanks for reporting the issue!

[xavierfigueroav]

I would like to take this issue!

[dbieber]

Excellent, thanks xavierfigueroav. Let me know if you need any pointers to get started.

[xavierfigueroav]

I think I got it, it was very simple. I guess I have to write tests for the change. If so, I need pointers on how to simulate the call python script.py command. I think that the following component is the most suitable for this case:

python-fire/fire/test_components.py

Lines 125 to 134 in 8e9b1d5

	class MixedDefaults(object):
	def ten(self):
	return 10
	def sum(self, alpha=0, beta=0):
	return alpha + 2 * beta
	def identity(self, alpha, beta='0'):
	return alpha, beta

But, I don't know how to simulate the call to identity from it. Just component = tc.MixedDefaults() or component = tc.MixedDefaults().identity doesn't seem to reproduce the case.

[xavierfigueroav]

It seems that the bare * actually matters 😅. I need something like

class Example:
    def command(self, *, arg1, arg2=True, arg3=False):
        pass

So, should I add a function like that to the MixedDefaults component or create a new component?

[xavierfigueroav]

Well, I opened #316. If any changes are needed, please, let me know.

[dzieciou]

What's the progress on that? 1 year passed and still a problem

[dbieber]

No new developments. Thanks for the ping.

The PR looks good -- should be able to merge it in my next fire working session (haven't had one recently, hence the issue going stale).