8000 gh-94601: [Enum] fix inheritance for __str__ and friends by ethanfurman · Pull Request #94942 · python/cpython · GitHub
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gh-94601: [Enum] fix inheritance for __str__ and friends #94942

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Merged
merged 1 commit into from
Jul 18, 2022
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gh-94601: [Enum] fix inheritance for __str__ and friends #94942

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26 changes: 21 additions & 5 deletions Lib/enum.py
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Original file line number Diff line number Diff line change
Expand Up @@ -247,7 +247,10 @@ def __set_name__(self, enum_class, member_name):
if not enum_class._use_args_:
enum_member = enum_class._new_member_(enum_class)
if not hasattr(enum_member, '_value_'):
enum_member._value_ = value
try:
enum_member._value_ = enum_class._member_type_(*args)
except Exception as exc:
enum_member._value_ = value
else:
enum_member = enum_class._new_member_(enum_class, *args)
if not hasattr(enum_member, '_value_'):
Expand Down Expand Up @@ -562,7 +565,13 @@ def __new__(metacls, cls, bases, classdict, *, boundary=None, _simple=False, **k
classdict['__str__'] = enum_class.__str__
for name in ('__repr__', '__str__', '__format__', '__reduce_ex__'):
if name not in classdict:
setattr(enum_class, name, getattr(first_enum, name))
# check for mixin overrides before replacing
enum_method = getattr(first_enum, name)
found_method = getattr(enum_class, name)
object_method = getattr(object, name)
data_type_method = getattr(member_type, name)
if found_method in (data_type_method, object_method):
setattr(enum_class, name, enum_method)
#
# for Flag, add __or__, __and__, __xor__, and __invert__
if Flag is not None and issubclass(enum_class, Flag):
Expand Down Expand Up @@ -937,16 +946,18 @@ def _find_data_repr_(mcls, class_name, bases):
@classmethod
def _find_data_type_(mcls, class_name, bases):
data_types = set()
base_chain = set()
for chain in bases:
candidate = None
for base in chain.__mro__:
base_chain.add(base)
if base is object:
continue
elif issubclass(base, Enum):
if base._member_type_ is not object:
data_types.add(base._member_type_)
break
elif '__new__' in base.__dict__:
elif '__new__' in base.__dict__ or '__init__' in base.__dict__:
if issubclass(base, Enum):
continue
data_types.add(candidate or base)
Expand Down Expand Up @@ -1650,7 +1661,13 @@ def convert_class(cls):
enum_class = type(cls_name, (etype, ), body, boundary=boundary, _simple=True)
for name in ('__repr__', '__str__', '__format__', '__reduce_ex__'):
if name not in body:
setattr(enum_class, name, getattr(etype, name))
# check for mixin overrides before replacing
enum_method = getattr(etype, name)
found_method = getattr(enum_class, name)
object_method = getattr(object, name)
data_type_method = getattr(member_type, name)
if found_method in (data_type_method, object_method):
setattr(enum_class, name, enum_method)
gnv_last_values = []
if issubclass(enum_class, Flag):
# Flag / IntFlag
Expand Down Expand Up @@ -1981,7 +1998,6 @@ def _old_convert_(etype, name, module, filter, source=None, *, boundary=None):
members.sort(key=lambda t: t[0])
cls = etype(name, members, module=module, boundary=boundary or KEEP)
cls.__reduce_ex__ = _reduce_ex_by_global_name
cls.__repr__ = global_enum_repr
return cls

_stdlib_enums = IntEnum, StrEnum, IntFlag
26 changes: 21 additions & 5 deletions Lib/test/test_enum.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2688,23 +2688,39 @@ def test_repr_with_dataclass(self):
@dataclass
class Foo:
__qualname__ = 'Foo'
a: int = 0
a: int
class Entries(Foo, Enum):
ENTRY1 = Foo(1)
ENTRY1 = 1
self.assertTrue(isinstance(Entries.ENTRY1, Foo))
self.assertTrue(Entries._member_type_ is Foo, Entries._member_type_)
self.assertTrue(Entries.ENTRY1.value == Foo(1), Entries.ENTRY1.value)
self.assertEqual(repr(Entries.ENTRY1), '<Entries.ENTRY1: Foo(a=1)>')

def test_repr_with_non_data_type_mixin(self):
def test_repr_with_init_data_type_mixin(self):
# non-data_type is a mixin that doesn't define __new__
class Foo:
def __init__(self, a):
self.a = a
def __repr__(self):
return f'Foo(a={self.a!r})'
class Entries(Foo, Enum):
ENTRY1 = Foo(1)

ENTRY1 = 1
#
self.assertEqual(repr(Entries.ENTRY1), '<Entries.ENTRY1: Foo(a=1)>')

def test_repr_and_str_with_non_data_type_mixin(self):
# non-data_type is a mixin that doesn't define __new__
class Foo:
def __repr__(self):
return 'Foo'
def __str__(self):
return 'ooF'
class Entries(Foo, Enum):
ENTRY1 = 1
#
self.assertEqual(repr(Entries.ENTRY1), 'Foo')
self.assertEqual(str(Entries.ENTRY1), 'ooF')

def test_value_backup_assign(self):
# check that enum will add missing values when custom __new__ does not
class Some(Enum):
Expand Down
0