#12776,#11839: call argparse type function only once.
Before, the type function was called twice in the case where the default
was specified and the argument was given as well. This was 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.
Patch by Arnaud Fontaine, with additional test by Mike Meyer.
diff --git a/Lib/argparse.py b/Lib/argparse.py
index 80df97b..a738455 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1705,10 +1705,7 @@
if action.dest is not SUPPRESS:
if not hasattr(namespace, action.dest):
if action.default is not SUPPRESS:
- default = action.default
- if isinstance(action.default, basestring):
- default = self._get_value(action, default)
- setattr(namespace, action.dest, default)
+ setattr(namespace, action.dest, action.default)
# add any parser defaults that aren't present
for dest in self._defaults:
@@ -1936,12 +1933,22 @@
if positionals:
self.error(_('too few arguments'))
- # make sure all required actions were present
+ # make sure all required actions were present, and convert defaults.
for action in self._actions:
- if action.required:
- if action not in seen_actions:
+ if action not in seen_actions:
+ if action.required:
name = _get_action_name(action)
self.error(_('argument %s is required') % name)
+ else:
+ # Convert action default now instead of doing it before
+ # parsing arguments to avoid calling convert functions
+ # 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
+ hasattr(namespace, action.dest) and
+ action.default is getattr(namespace, action.dest)):
+ setattr(namespace, action.dest,
+ self._get_value(action, action.default))
# make sure all required groups had one option present
for group in self._mutually_exclusive_groups:
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 80dbc22..77f5aca 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1467,6 +1467,22 @@
('readonly', NS(x=None, spam=RFile('readonly'))),
]
+class TestFileTypeDefaults(TempDirMixin, ParserTestCase):
+ """Test that a file is not created unless the default is needed"""
+ def setUp(self):
+ super(TestFileTypeDefaults, self).setUp()
+ file = open(os.path.join(self.temp_dir, 'good'), 'w')
+ file.write('good')
+ file.close()
+
+ argument_signatures = [
+ Sig('-c', type=argparse.FileType('r'), default='no-file.txt'),
+ ]
+ # should provoke no such file error
+ failures = ['']
+ # should not provoke error because default file is created
+ successes = [('-c good', NS(c=RFile('good')))]
+
class TestFileTypeRB(TempDirMixin, ParserTestCase):
"""Test the FileType option/argument type for reading files"""
@@ -4432,6 +4448,38 @@
else:
self.fail()
+# ================================================
+# Check that the type function is called only once
+# ================================================
+
+class TestTypeFunctionCallOnlyOnce(TestCase):
+
+ def test_type_function_call_only_once(self):
+ def spam(string_to_convert):
+ self.assertEqual(string_to_convert, 'spam!')
+ return 'foo_converted'
+
+ parser = argparse.ArgumentParser()
+ parser.add_argument('--foo', type=spam, default='bar')
+ args = parser.parse_args('--foo spam!'.split())
+ self.assertEqual(NS(foo='foo_converted'), args)
+
+# ================================================================
+# Check that the type function is called with a non-string default
+# ================================================================
+
+class TestTypeFunctionCallWithNonStringDefault(TestCase):
+
+ def test_type_function_call_with_non_string_default(self):
+ def spam(int_to_convert):
+ self.assertEqual(int_to_convert, 0)
+ return 'foo_converted'
+
+ parser = argparse.ArgumentParser()
+ parser.add_argument('--foo', type=spam, default=0)
+ args = parser.parse_args([])
+ self.assertEqual(NS(foo='foo_converted'), args)
+
# ======================
# parse_known_args tests
# ======================
diff --git a/Misc/ACKS b/Misc/ACKS
index d8ddd32..2a93d66 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -271,6 +271,7 @@
Frederik Fix
Matt Fleming
Hernán Martínez Foffani
+Arnaud Fontaine
Michael Foord
Amaury Forgeot d'Arc
Doug Fort
diff --git a/Misc/NEWS b/Misc/NEWS
index f13499f..bdfd0b7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -98,6 +98,12 @@
Library
-------
+- Issue #12776,#11839: call argparse type function (specified by add_argument)
+ only once. Before, the type function was called twice in the case where the
+ default was specified and the argument was given as well. This was
+ 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 #13370: Ensure that ctypes works on Mac OS X when Python is
compiled using the clang compiler