There's an obligatory XKCD reference for this: http://xkcd.com/1172/
On Tue, Jan 6, 2015 at 12:25 PM, Terry Reedy <tjre...@udel.edu> wrote: > On 1/6/2015 7:39 AM, Victor Stinner wrote: > >> More context: >> >> 2014-12-19 12:43 GMT+01:00 anatoly techtonik <techto...@gmail.com>: >> >>> https://github.com/nickstenning/honcho/pull/121 >>> >> >> The link mentions the following changeset: >> --- >> changeset: 93122:1a3143752db2 >> branch: 2.7 >> parent: 93112:927cca0b9337 >> user: R David Murray <rdmur...@bitdance.com> >> date: Fri Oct 17 20:07:08 2014 -0400 >> files: Lib/argparse.py Lib/test/test_argparse.py Misc/NEWS >> description: >> #9351: set_defaults on subparser is no longer ignored if set on parent. >> >> Before, if a default was set on the parent parser, any default for that >> variable set via set_defaults on a subparser would be ignored. Now >> the subparser set_defaults is honored. >> >> Patch by Jyrki Pullianinen. >> >> >> diff -r 927cca0b9337 -r 1a3143752db2 Lib/argparse.py >> --- a/Lib/argparse.py Fri Oct 17 16:20:15 2014 -0500 >> +++ b/Lib/argparse.py Fri Oct 17 20:07:08 2014 -0400 >> @@ -1089,7 +1089,14 @@ class _SubParsersAction(Action): >> # parse all the remaining options into the namespace >> # store any unrecognized options on the object, so that the top >> # level parser can decide what to do with them >> - namespace, arg_strings = parser.parse_known_args(arg_strings, >> namespace) >> + >> + # In case this subparser defines new defaults, we parse them >> + # in a new namespace object and then update the original >> + # namespace for the relevant parts. >> + subnamespace, arg_strings = parser.parse_known_args(arg_strings, >> None) >> + for key, value in vars(subnamespace).items(): >> + setattr(namespace, key, value) >> + >> if arg_strings: >> vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, []) >> getattr(namespace, _UNRECOGNIZED_ARGS_ATTR). >> extend(arg_strings) >> --- >> >> Which is related to http://bugs.python.org/issue9351 >> >> Maybe argparse just became more strict? I don't understand the issue. >> > > Steven Bethard, the argparse maintainer, defined the old behavior of > ignoring subparser defaults (where there are also top level defaults) as a > bug "counter to what people probably expect". If the old behavior had been > documented, changing it in a bug-fix release would have been a mistake. > But looking at the patch, the doc seems to have been silent on the issue. > > This is not the first time someone considered a 'bug fix' to be a > 'regression', which it might be from their viewpoint. The last comment on > the github thread suggests that an easy fix was found. > > -- > Terry Jan Reedy > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > guido%40python.org > -- --Guido van Rossum (python.org/~guido)
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