Jorge L. Martinez <j...@fastmail.com> added the comment:

> There are earlier bug/issues about the '--'.

Yes, there are:

https://bugs.python.org/issue9571
https://bugs.python.org/issue22223
https://bugs.python.org/issue14364

But this one seems separate. Though they're related, they don't seem like 
duplicates, so that's why I thought I'd make this one.

> Also look at the parser code itself.  Keep in mind that parsing is done in 
> two passes - once to identify flags versus arguments ('O/A') and then to 
> allocate strings to arguments. I don't recall when '--' is being handled, 
> possibly in both.

I'm not sure what your point is here. I did take a quick look at the code, 
yesterday. I think the identification part you mention is done right. It marks 
'O/A' as you mention. Then, when it sees "--", it marks it "-", and the rest of 
the arguments are marked as "A".

I didn't look at the start of the code of the second pass or how it is 
concretely linked to the first pass. However, I did see that in the example I 
gave, _get_values() in argparse.py gets called twice (apparently once per 
argument group as determined by nargs, I guess) to remove the "--" present in 
arg_strings. The first time, arg_strings is ["foo", "--"] and the second time 
it's ["bar", "--", "baz", "--", "zap"].

So, that's what happens, and where part of the fix should probably be. I don't 
think the removal of "--" should happen in a function that gets called multiple 
times. Though I didn't spend the time to see where the code should be 
positioned, I can only imagine the correct behavior would be to remove the 
argument marked as "-" by the first pass mentioned.

I didn't mention this yesterday, because I figured there wouldn't be much value 
in sharing incomplete research like this, as opposed to a patch. I didn't want 
to influence the work of whoever chose to invest time in this for a proper fix.

----------

_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37510>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

Reply via email to