[Python-checkins] bpo-44356: [Enum] allow multiple data-type mixins if they are all the same (GH-26649) (GH-26652)
ethanfurman
webhook-mailer at python.org
Thu Jun 10 18:03:37 EDT 2021
https://github.com/python/cpython/commit/304ec53b53021ceddf62a38e66a06aed37e2ac41
commit: 304ec53b53021ceddf62a38e66a06aed37e2ac41
branch: 3.9
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: ethanfurman <ethan at stoneleaf.us>
date: 2021-06-10T15:03:29-07:00
summary:
bpo-44356: [Enum] allow multiple data-type mixins if they are all the same (GH-26649) (GH-26652)
This enables, for example, two base Enums to both inherit from `str`, and then both be mixed into the same final Enum:
class Str1Enum(str, Enum):
GH- some behavior here
class Str2Enum(str, Enum):
GH- some more behavior here
class FinalStrEnum(Str1Enum, Str2Enum):
GH- this now works
(cherry picked from commit 8a4f0850d75747af8c96ca0e7eef1f5c1abfba25)
Co-authored-by: Ethan Furman <ethan at stoneleaf.us>
Co-authored-by: Ethan Furman <ethan at stoneleaf.us>
files:
A Misc/NEWS.d/next/Library/2021-06-10-08-35-38.bpo-44356.6oDFhO.rst
M Lib/enum.py
M Lib/test/test_enum.py
diff --git a/Lib/enum.py b/Lib/enum.py
index be74796a8a0ce..f09cb8473dfed 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -556,7 +556,7 @@ def _get_mixins_(class_name, bases):
return object, Enum
def _find_data_type(bases):
- data_types = []
+ data_types = set()
for chain in bases:
candidate = None
for base in chain.__mro__:
@@ -564,19 +564,19 @@ def _find_data_type(bases):
continue
elif issubclass(base, Enum):
if base._member_type_ is not object:
- data_types.append(base._member_type_)
+ data_types.add(base._member_type_)
break
elif '__new__' in base.__dict__:
if issubclass(base, Enum):
continue
- data_types.append(candidate or base)
+ data_types.add(candidate or base)
break
else:
candidate = base
if len(data_types) > 1:
raise TypeError('%r: too many data types: %r' % (class_name, data_types))
elif data_types:
- return data_types[0]
+ return data_types.pop()
else:
return None
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index fc2d61d59cd4b..e8715ba34552b 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -2072,6 +2072,53 @@ def __new__(cls, value):
return member
self.assertEqual(Fee.TEST, 2)
+ def test_miltuple_mixin_with_common_data_type(self):
+ class CaseInsensitiveStrEnum(str, Enum):
+ @classmethod
+ def _missing_(cls, value):
+ for member in cls._member_map_.values():
+ if member._value_.lower() == value.lower():
+ return member
+ return super()._missing_(value)
+ #
+ class LenientStrEnum(str, Enum):
+ def __init__(self, *args):
+ self._valid = True
+ @classmethod
+ def _missing_(cls, value):
+ # encountered an unknown value!
+ # Luckily I'm a LenientStrEnum, so I won't crash just yet.
+ # You might want to add a new case though.
+ unknown = cls._member_type_.__new__(cls, value)
+ unknown._valid = False
+ unknown._name_ = value.upper()
+ unknown._value_ = value
+ cls._member_map_[value] = unknown
+ return unknown
+ @property
+ def valid(self):
+ return self._valid
+ #
+ class JobStatus(CaseInsensitiveStrEnum, LenientStrEnum):
+ ACTIVE = "active"
+ PENDING = "pending"
+ TERMINATED = "terminated"
+ #
+ JS = JobStatus
+ self.assertEqual(list(JobStatus), [JS.ACTIVE, JS.PENDING, JS.TERMINATED])
+ self.assertEqual(JS.ACTIVE, 'active')
+ self.assertEqual(JS.ACTIVE.value, 'active')
+ self.assertIs(JS('Active'), JS.ACTIVE)
+ self.assertTrue(JS.ACTIVE.valid)
+ missing = JS('missing')
+ self.assertEqual(list(JobStatus), [JS.ACTIVE, JS.PENDING, JS.TERMINATED])
+ self.assertEqual(JS.ACTIVE, 'active')
+ self.assertEqual(JS.ACTIVE.value, 'active')
+ self.assertIs(JS('Active'), JS.ACTIVE)
+ self.assertTrue(JS.ACTIVE.valid)
+ self.assertTrue(isinstance(missing, JS))
+ self.assertFalse(missing.valid)
+
def test_empty_globals(self):
# bpo-35717: sys._getframe(2).f_globals['__name__'] fails with KeyError
# when using compile and exec because f_globals is empty
diff --git a/Misc/NEWS.d/next/Library/2021-06-10-08-35-38.bpo-44356.6oDFhO.rst b/Misc/NEWS.d/next/Library/2021-06-10-08-35-38.bpo-44356.6oDFhO.rst
new file mode 100644
index 0000000000000..954a803fe25c1
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-06-10-08-35-38.bpo-44356.6oDFhO.rst
@@ -0,0 +1 @@
+[Enum] Allow multiple data-type mixins if they are all the same.
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