[docs] [issue14191] argparse doesn't allow optionals within positionals

[Glenn Linderman]

Glenn Linderman <v+python at g.nevcal.com> added the comment:

So my t18a.py wraps Argparse, because the externals are documented and I could understand that. Given enough time, I might be able to understand the internals too... it is just Python...

Seems like the internals separate positionals and optionals into two subparsers, the logic needed is to save the positionals, temporarily replace them with an empty group, and call parse_known_args, then restore the positionals, and call parse_known_args again.

What I haven't figured out, is how that would affect the help message building, and how to make the empty group of positionals without affecting the help message.

It's also not clear that it is possible, with current internals, to substitute an empty group... the only features for creating a group seem to always add it to a list of _action_groups.  So that muddies the water, just like the help message... everything seems intertwined internally.

A little guidance here, would let me code... I could probably whack and slash, and keep extra lists of arguments and sort of make it work like my wrapper does, but I doubt that would be an acceptable patch. So I would be happy, with guidance, to try to create the code, and I can do a "diff", but beyond that, I'm sort of at a loss.

So I'd be happy to work with someone to create the patch, but I've also never created a patch, nor test cases, for Python (or any other open source project). Theoretically, it is straightforward, and documented; as a practical matter, it isn't likely that I'll find time to figure out all that methodology and actually create a patch, in the near future (although it is on my list of things to learn, in the fullness of time, and after the first one, I'm sure subsequent ones would be easier).

Or if someone else wants to code it, I'd be happy to look it over, test it with my environment and applications that I'm currently using with my wrapper.

Given this guidance, I've tweaked my wrapper to have parse_intermixed_args rather than changing the behavior of parse_args as I have been, and will tweak the apps correspondingly, so I'll be in a position to test any code created for this issue.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue14191>
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