Close #18989: enum members will no longer overwrite other attributes, nor be overwritten by them.
diff --git a/Lib/enum.py b/Lib/enum.py
index 0d72f3e..40546da 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -29,6 +29,14 @@
raise AttributeError("can't delete attribute")
+def _is_descriptor(obj):
+ """Returns True if obj is a descriptor, False otherwise."""
+ return (
+ hasattr(obj, '__get__') or
+ hasattr(obj, '__set__') or
+ hasattr(obj, '__delete__'))
+
+
def _is_dunder(name):
"""Returns True if a __dunder__ name, False otherwise."""
return (name[:2] == name[-2:] == '__' and
@@ -50,8 +58,9 @@
cls.__reduce__ = _break_on_call_reduce
cls.__module__ = '<unknown>'
+
class _EnumDict(dict):
- """Keeps track of definition order of the enum items.
+ """Track enum member order and ensure member names are not reused.
EnumMeta will use the names found in self._member_names as the
enumeration member names.
@@ -62,11 +71,7 @@
self._member_names = []
def __setitem__(self, key, value):
- """Changes anything not dundered or that doesn't have __get__.
-
- If a descriptor is added with the same name as an enum member, the name
- is removed from _member_names (this may leave a hole in the numerical
- sequence of values).
+ """Changes anything not dundered or not a descriptor.
If an enum member name is used twice, an error is raised; duplicate
values are not checked for.
@@ -76,19 +81,20 @@
"""
if _is_sunder(key):
raise ValueError('_names_ are reserved for future Enum use')
- elif _is_dunder(key) or hasattr(value, '__get__'):
- if key in self._member_names:
- # overwriting an enum with a method? then remove the name from
- # _member_names or it will become an enum anyway when the class
- # is created
- self._member_names.remove(key)
- else:
- if key in self._member_names:
- raise TypeError('Attempted to reuse key: %r' % key)
+ elif _is_dunder(key):
+ pass
+ elif key in self._member_names:
+ # descriptor overwriting an enum?
+ raise TypeError('Attempted to reuse key: %r' % key)
+ elif not _is_descriptor(value):
+ if key in self:
+ # enum overwriting a descriptor?
+ raise TypeError('Key already defined as: %r' % self[key])
self._member_names.append(key)
super().__setitem__(key, value)
+
# Dummy value for Enum as EnumMeta explicitly checks for it, but of course
# until EnumMeta finishes running the first time the Enum class doesn't exist.
# This is also why there are checks in EnumMeta like `if Enum is not None`