[Python-checkins] cpython (3.4): #9351: set_defaults on subparser is no longer ignored if set on parent.

[r.david.murray]

https://hg.python.org/cpython/rev/e9cb45ccf42b
changeset:   93120:e9cb45ccf42b
branch:      3.4
parent:      93118:fea3ddcaf652
user:        R David Murray <rdmurray at bitdance.com>
date:        Fri Oct 17 19:55:11 2014 -0400
summary:
  #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.

files:
  Lib/argparse.py           |  9 ++++++++-
  Lib/test/test_argparse.py |  7 +++++++
  Misc/NEWS                 |  3 +++
  3 files changed, 18 insertions(+), 1 deletions(-)


diff --git a/Lib/argparse.py b/Lib/argparse.py
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1122,7 +1122,14 @@
         # 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)
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
@@ -2795,6 +2795,13 @@
         parser = ErrorRaisingArgumentParser(parents=[parent])
         self.assertEqual(NS(x='foo'), parser.parse_args([]))
 
+    def test_set_defaults_on_parent_and_subparser(self):
+        parser = argparse.ArgumentParser()
+        xparser = parser.add_subparsers().add_parser('X')
+        parser.set_defaults(foo=1)
+        xparser.set_defaults(foo=2)
+        self.assertEqual(NS(foo=2), parser.parse_args(['X']))
+
     def test_set_defaults_same_as_add_argument(self):
         parser = ErrorRaisingArgumentParser()
         parser.set_defaults(w='W', x='X', y='Y', z='Z')
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -33,6 +33,9 @@
 Library
 -------
 
+- Issue #9351: Defaults set with set_defaults on an argparse subparser
+  are no longer ignored when also set on the parent parser.
+
 - Issue #21991: Make email.headerregistry's header 'params' attributes
   be read-only (MappingProxyType).  Previously the dictionary was modifiable
   but a new one was created on each access of the attribute.

-- 
Repository URL: https://hg.python.org/cpython