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
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