diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst index a3c51655576..4ecca209d87 100644 --- a/Doc/library/enum.rst +++ b/Doc/library/enum.rst @@ -1121,6 +1121,15 @@ and raise an error if the two do not match:: In Python 2 code the :attr:`_order_` attribute is necessary as definition order is lost before it can be recorded. + +_Private__names +""""""""""""""" + +Private names will be normal attributes in Python 3.10 instead of either an error +or a member (depending on if the name ends with an underscore). Using these names +in 3.9 will issue a :exc:`DeprecationWarning`. + + ``Enum`` member type """""""""""""""""""" diff --git a/Lib/enum.py b/Lib/enum.py index 35210c99332..46b5435b7c8 100644 --- a/Lib/enum.py +++ b/Lib/enum.py @@ -41,6 +41,19 @@ def _is_sunder(name): name[-2:-1] != '_' ) +def _is_private(cls_name, name): + # do not use `re` as `re` imports `enum` + pattern = '_%s__' % (cls_name, ) + if ( + len(name) >= 5 + and name.startswith(pattern) + and name[len(pattern)] != '_' + and (name[-1] != '_' or name[-2] != '_') + ): + return True + else: + return False + def _make_class_unpicklable(cls): """ Make the given class un-picklable. @@ -81,6 +94,14 @@ class _EnumDict(dict): Single underscore (sunder) names are reserved. """ + if _is_private(self._cls_name, key): + import warnings + warnings.warn( + "private variables, such as %r, will be normal attributes in 3.10" + % (key, ), + DeprecationWarning, + stacklevel=2, + ) if _is_sunder(key): if key not in ( '_order_', '_create_pseudo_member_', @@ -146,6 +167,7 @@ class EnumMeta(type): metacls._check_for_existing_members(cls, bases) # create the namespace dict enum_dict = _EnumDict() + enum_dict._cls_name = cls # inherit previous flags and _generate_next_value_ function member_type, first_enum = metacls._get_mixins_(cls, bases) if first_enum is not None: diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py index dca668a9046..f7f8522bda4 100644 --- a/Lib/test/test_enum.py +++ b/Lib/test/test_enum.py @@ -1147,6 +1147,7 @@ class TestEnum(unittest.TestCase): class auto_enum(type(Enum)): def __new__(metacls, cls, bases, classdict): temp = type(classdict)() + temp._cls_name = cls names = set(classdict._member_names) i = 0 for k in classdict._member_names: @@ -2049,6 +2050,23 @@ class TestEnum(unittest.TestCase): exec(code, global_ns, local_ls) + @unittest.skipUnless( + sys.version_info[:2] == (3, 9), + 'private variables are now normal attributes', + ) + def test_warning_for_private_variables(self): + with self.assertWarns(DeprecationWarning): + class Private(Enum): + __corporal = 'Radar' + self.assertEqual(Private._Private__corporal.value, 'Radar') + try: + with self.assertWarns(DeprecationWarning): + class Private(Enum): + __major_ = 'Hoolihan' + except ValueError: + pass + + class TestOrder(unittest.TestCase): def test_same_members(self): diff --git a/Misc/NEWS.d/next/Library/2020-12-09-10-59-16.bpo-42517.FKEVcZ.rst b/Misc/NEWS.d/next/Library/2020-12-09-10-59-16.bpo-42517.FKEVcZ.rst new file mode 100644 index 00000000000..e99294d9430 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-12-09-10-59-16.bpo-42517.FKEVcZ.rst @@ -0,0 +1,2 @@ +Enum: private names will raise a DeprecationWarning; in 3.10 they will +become normal attributes