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bpo-44342: [Enum] changed pickling from by-value to by-name (GH-26658) (GH-26660)

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by-value lookups could fail on complex enums, necessitating a check for
__reduce__ and possibly sabotaging the final enum;

by-name lookups should never fail, and sabotaging is no longer necessary
for class-based enum creation.
(cherry picked from commit 62f1d2b3d7)

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
This commit is contained in:
Miss Islington (bot) 2021-06-10 16:37:27 -07:00 • committed by GitHub
parent 3e137426de
commit b613132861
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3 changed files with 9 additions and 25 deletions
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25
Lib/enum.py
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@ -456,23 +456,6 @@ class EnumType(type):
classdict['_all_bits_'] = 2 ** ((flag_mask).bit_length()) - 1 classdict['_all_bits_'] = 2 ** ((flag_mask).bit_length()) - 1
classdict['_inverted_'] = None classdict['_inverted_'] = None
# #
# If a custom type is mixed into the Enum, and it does not know how
# to pickle itself, pickle.dumps will succeed but pickle.loads will
# fail. Rather than have the error show up later and possibly far
# from the source, sabotage the pickle protocol for this class so
# that pickle.dumps also fails.
#
# However, if the new class implements its own __reduce_ex__, do not
# sabotage -- it's on them to make sure it works correctly. We use
# __reduce_ex__ instead of any of the others as it is preferred by
# pickle over __reduce__, and it handles all pickle protocols.
if '__reduce_ex__' not in classdict:
if member_type is not object:
methods = ('__getnewargs_ex__', '__getnewargs__',
'__reduce_ex__', '__reduce__')
if not any(m in member_type.__dict__ for m in methods):
_make_class_unpicklable(classdict)
#
# create a default docstring if one has not been provided # create a default docstring if one has not been provided
if '__doc__' not in classdict: if '__doc__' not in classdict:
classdict['__doc__'] = 'An enumeration.' classdict['__doc__'] = 'An enumeration.'
@ -792,7 +775,7 @@ class EnumType(type):
body['__module__'] = module body['__module__'] = module
tmp_cls = type(name, (object, ), body) tmp_cls = type(name, (object, ), body)
cls = _simple_enum(etype=cls, boundary=boundary or KEEP)(tmp_cls) cls = _simple_enum(etype=cls, boundary=boundary or KEEP)(tmp_cls)
cls.__reduce_ex__ = _reduce_ex_by_name cls.__reduce_ex__ = _reduce_ex_by_global_name
global_enum(cls) global_enum(cls)
module_globals[name] = cls module_globals[name] = cls
return cls return cls
@ -1030,7 +1013,7 @@ class Enum(metaclass=EnumType):
return hash(self._name_) return hash(self._name_)
def __reduce_ex__(self, proto): def __reduce_ex__(self, proto):
return self.__class__, (self._value_, ) return getattr, (self.__class__, self._name_)
# enum.property is used to provide access to the `name` and # enum.property is used to provide access to the `name` and
# `value` attributes of enum members while keeping some measure of # `value` attributes of enum members while keeping some measure of
@ -1091,7 +1074,7 @@ class StrEnum(str, Enum):
return name.lower() return name.lower()
def _reduce_ex_by_name(self, proto): def _reduce_ex_by_global_name(self, proto):
return self.name return self.name
class FlagBoundary(StrEnum): class FlagBoundary(StrEnum):
@ -1795,6 +1778,6 @@ def _old_convert_(etype, name, module, filter, source=None, *, boundary=None):
# unless some values aren't comparable, in which case sort by name # unless some values aren't comparable, in which case sort by name
members.sort(key=lambda t: t[0]) members.sort(key=lambda t: t[0])
cls = etype(name, members, module=module, boundary=boundary or KEEP) cls = etype(name, members, module=module, boundary=boundary or KEEP)
cls.__reduce_ex__ = _reduce_ex_by_name cls.__reduce_ex__ = _reduce_ex_by_global_name
cls.__repr__ = global_enum_repr cls.__repr__ = global_enum_repr
return cls return cls

8
Lib/test/test_enum.py
View file

@ -830,7 +830,7 @@ class TestEnum(unittest.TestCase):
class ReplaceGlobalInt(IntEnum): class ReplaceGlobalInt(IntEnum):
ONE = 1 ONE = 1
TWO = 2 TWO = 2
ReplaceGlobalInt.__reduce_ex__ = enum._reduce_ex_by_name ReplaceGlobalInt.__reduce_ex__ = enum._reduce_ex_by_global_name
for proto in range(HIGHEST_PROTOCOL): for proto in range(HIGHEST_PROTOCOL):
self.assertEqual(ReplaceGlobalInt.TWO.__reduce_ex__(proto), 'TWO') self.assertEqual(ReplaceGlobalInt.TWO.__reduce_ex__(proto), 'TWO')
@ -1527,10 +1527,10 @@ class TestEnum(unittest.TestCase):
NI5 = NamedInt('test', 5) NI5 = NamedInt('test', 5)
self.assertEqual(NI5, 5) self.assertEqual(NI5, 5)
self.assertEqual(NEI.y.value, 2) self.assertEqual(NEI.y.value, 2)
test_pickle_exception(self.assertRaises, TypeError, NEI.x) test_pickle_dump_load(self.assertIs, NEI.y)
test_pickle_exception(self.assertRaises, PicklingError, NEI) test_pickle_dump_load(self.assertIs, NEI)
def test_subclasses_without_direct_pickle_support_using_name(self): def test_subclasses_with_direct_pickle_support(self):
class NamedInt(int): class NamedInt(int):
__qualname__ = 'NamedInt' __qualname__ = 'NamedInt'
def __new__(cls, *args): def __new__(cls, *args):

1
Misc/NEWS.d/next/Library/2021-06-10-15-06-47.bpo-44342.qqkGlj.rst Normal file
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@ -0,0 +1 @@
[Enum] Change pickling from by-value to by-name.