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3 changes: 3 additions & 0 deletions Doc/library/argparse.rst
Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,9 @@ ArgumentParser objects
.. versionchanged:: 3.15
*suggest_on_error* default changed to ``True``.

.. versionchanged:: next
:class:`~argparse.ArgumentParser` objects are now :mod:`pickleable <pickle>`.

The following sections describe how each of these are used.


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10 changes: 6 additions & 4 deletions Lib/argparse.py
Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,10 @@ def _copy_items(items):
return copy.copy(items)


def _identity(value):
return value


# ===============
# Formatting Help
# ===============
Expand Down Expand Up @@ -199,7 +203,7 @@ def _set_color(self, color, *, file=None):
self._decolor = decolor
else:
self._theme = get_theme(force_no_color=True).argparse
self._decolor = lambda text: text
self._decolor = _identity

# ===============================
# Section and indentation methods
Expand Down Expand Up @@ -1981,9 +1985,7 @@ def __init__(self,
self._subparsers = None

# register types
def identity(string):
return string
self.register('type', None, identity)
self.register('type', None, _identity)

# add help argument if necessary
# (using explicit default to override global argument_default)
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21 changes: 21 additions & 0 deletions Lib/test/test_argparse.py
Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,27 @@ def test_skip_invalid_stdout(self):
self.assertRegex(mocked_stderr.getvalue(), r'usage:')


class TestArgumentParserPickleable(unittest.TestCase):

@force_not_colorized
def test_pickle_roundtrip(self):
import pickle
parser = argparse.ArgumentParser(exit_on_error=False)
parser.add_argument('--foo', type=int, default=42)
parser.add_argument('bar', nargs='?', default='baz')
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
with self.subTest(protocol=proto):
# Try to pickle and unpickle the parser
parser2 = pickle.loads(pickle.dumps(parser, protocol=proto))
# Check that the round-tripped parser still works
ns = parser2.parse_args(['--foo', '123', 'quux'])
self.assertEqual(ns.foo, 123)
self.assertEqual(ns.bar, 'quux')
ns2 = parser2.parse_args([])
self.assertEqual(ns2.foo, 42)
self.assertEqual(ns2.bar, 'baz')


class TestCase(unittest.TestCase):

def setUp(self):
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Make :class:`argparse.ArgumentParser` :mod:`pickleable <pickle>`.
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