bpo-45235: Fix argparse overrides namespace with subparser defaults (GH-28420) (GH-28442)
diff --git a/Lib/argparse.py b/Lib/argparse.py
index 2ded39a..ce4635a 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1208,7 +1208,8 @@ def __call__(self, parser, namespace, values, option_string=None):
# 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 not hasattr(namespace, key):
+ setattr(namespace, key, value)
if arg_strings:
vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, [])
@@ -1842,11 +1843,6 @@ def parse_known_args(self, args=None, namespace=None):
if action.default is not SUPPRESS:
setattr(namespace, action.dest, action.default)
- # add any parser defaults that aren't present
- for dest in self._defaults:
- if not hasattr(namespace, dest):
- setattr(namespace, dest, self._defaults[dest])
-
# parse the arguments and exit if there are any errors
if self.exit_on_error:
try:
@@ -1857,6 +1853,11 @@ def parse_known_args(self, args=None, namespace=None):
else:
namespace, args = self._parse_known_args(args, namespace)
+ # add any parser defaults that aren't present
+ for dest in self._defaults:
+ if not hasattr(namespace, dest):
+ setattr(namespace, dest, self._defaults[dest])
+
if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR):
args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR))
delattr(namespace, _UNRECOGNIZED_ARGS_ATTR)
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index f453f60..376aa61 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -3060,6 +3060,12 @@ def test_set_defaults_on_parent_and_subparser(self):
xparser.set_defaults(foo=2)
self.assertEqual(NS(foo=2), parser.parse_args(['X']))
+ def test_set_defaults_on_subparser_with_namespace(self):
+ parser = argparse.ArgumentParser()
+ xparser = parser.add_subparsers().add_parser('X')
+ xparser.set_defaults(foo=1)
+ self.assertEqual(NS(foo=2), parser.parse_args(['X'], NS(foo=2)))
+
def test_set_defaults_same_as_add_argument(self):
parser = ErrorRaisingArgumentParser()
parser.set_defaults(w='W', x='X', y='Y', z='Z')