On Tue, Sep 11, 2012 at 9:13 PM, barry.warsaw <python-check...@python.org> wrote: > http://hg.python.org/cpython/rev/25e41fdc4e60 > changeset: 79001:25e41fdc4e60 > parent: 78998:6fea947edead > parent: 79000:bc342cd7ed96 > user: Barry Warsaw <ba...@python.org> > date: Wed Sep 12 00:12:29 2012 -0400 > summary: > - Issue #15906: Fix a regression in argparse caused by the preceding change, > when action='append', type='str' and default=[].
I didn't have time to respond Barry's e-mail from four hours ago before this was committed. I think this change may be problematic. At the least, I think people should have an opportunity to air their specific concerns and talk through the implications. Also, from the discussion it seemed like the sentiment was leaning towards a different approach for the fix. I made a comment on the issue with some more extended remarks: http://bugs.python.org/msg170351 --Chris > > files: > Lib/argparse.py | 1 + > Lib/test/test_argparse.py | 10 ++++++++++ > Misc/NEWS | 3 +++ > 3 files changed, 14 insertions(+), 0 deletions(-) > > > diff --git a/Lib/argparse.py b/Lib/argparse.py > --- a/Lib/argparse.py > +++ b/Lib/argparse.py > @@ -1961,6 +1961,7 @@ > # twice (which may fail) if the argument was given, but > # only if it was defined already in the namespace > if (action.default is not None and > + isinstance(action, _StoreAction) and > hasattr(namespace, action.dest) and > action.default is getattr(namespace, action.dest)): > setattr(namespace, action.dest, > diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py > --- a/Lib/test/test_argparse.py > +++ b/Lib/test/test_argparse.py > @@ -4607,6 +4607,16 @@ > args = parser.parse_args([]) > self.assertEqual(NS(foo='foo_converted'), args) > > + def test_issue_15906(self): > + # Issue #15906: When action='append', type=str, default=[] are > + # providing, the dest value was the string representation "[]" when > it > + # should have been an empty list. > + parser = argparse.ArgumentParser() > + parser.add_argument('--test', dest='test', type=str, > + default=[], action='append') > + args = parser.parse_args([]) > + self.assertEqual(args.test, []) > + > # ====================== > # parse_known_args tests > # ====================== > diff --git a/Misc/NEWS b/Misc/NEWS > --- a/Misc/NEWS > +++ b/Misc/NEWS > @@ -56,6 +56,9 @@ > especially problematic for the FileType type, as a default file would > always > be opened, even if a file argument was specified on the command line. > > +- Issue #15906: Fix a regression in argparse caused by the preceding change, > + when action='append', type='str' and default=[]. > + > Extension Modules > ----------------- > > > -- > Repository URL: http://hg.python.org/cpython > > _______________________________________________ > Python-checkins mailing list > python-check...@python.org > http://mail.python.org/mailman/listinfo/python-checkins > _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
