Martin Pengelly-Phillips <d...@thesociable.net> added the comment:
The real issue is that the choices flag does not work with a default flag and *
nargs.
The following works as expected:
>>> parser.add_argument('chosen', nargs='*', default=['a'])
>>> print(parser.parse_args())
Namespace(chosen=['a'])
>>> print(parser.parse_args(['a', 'b']))
Namespace(chosen=['a', 'b'])
Introducing a choices constraint breaks down when using the defaults:
>>> parser.add_argument('chosen', nargs='*', default=['a'], choices=['a', 'b'])
>>> print(parser.parse_args(['a']))
Namespace(chosen=['a'])
>>> print(parser.parse_args())
error: argument chosen: invalid choice: ['a'] (choose from 'a', 'b')
I would expect instead to have Namespace.chosen populated with the default list
as before, but the choices constraint check does not validate correctly.
I think that changing the choices constraint logic to iterate over the default
values if nargs results in a list would be a possible solution.
----------
title: argparse: Problem with defaults for variable nargs -> argparse: Problem
with defaults for variable nargs when using choices
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue9625>
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