remove custom Enums and use Enum._missing_ for missing values

Author: DA-344

discord/enums.py

@@ -25,9 +25,9 @@
 
 from __future__ import annotations
 
+from enum import Enum as EnumBase
 import types
-from collections import namedtuple
-from typing import TYPE_CHECKING, Any, ClassVar, TypeVar, Union
+from typing import Any, Self, TypeVar, Union
 
 __all__ = (
     "Enum",
@@ -83,118 +83,27 @@
 )
 
 
-def _create_value_cls(name, comparable):
-    cls = namedtuple(f"_EnumValue_{name}", "name value")
-    cls.__repr__ = lambda self: f"<{name}.{self.name}: {self.value!r}>"
-    cls.__str__ = lambda self: f"{name}.{self.name}"
-    if comparable:
-        cls.__le__ = lambda self, other: isinstance(other, self.__class__) and self.value <= other.value
-        cls.__ge__ = lambda self, other: isinstance(other, self.__class__) and self.value >= other.value
-        cls.__lt__ = lambda self, other: isinstance(other, self.__class__) and self.value < other.value
-        cls.__gt__ = lambda self, other: isinstance(other, self.__class__) and self.value > other.value
-    return cls
-
-
-def _is_descriptor(obj):
-    return hasattr(obj, "__get__") or hasattr(obj, "__set__") or hasattr(obj, "__delete__")
-
-
-class EnumMeta(type):
-    if TYPE_CHECKING:
-        __name__: ClassVar[str]
-        _enum_member_names_: ClassVar[list[str]]
-        _enum_member_map_: ClassVar[dict[str, Any]]
-        _enum_value_map_: ClassVar[dict[Any, Any]]
-
-    def __new__(cls, name, bases, attrs, *, comparable: bool = False):
-        value_mapping = {}
-        member_mapping = {}
-        member_names = []
-
-        value_cls = _create_value_cls(name, comparable)
-        for key, value in list(attrs.items()):
-            is_descriptor = _is_descriptor(value)
-            if key[0] == "_" and not is_descriptor:
-                continue
-
-            # Special case classmethod to just pass through
-            if isinstance(value, classmethod):
-                continue
-
-            if is_descriptor:
-                setattr(value_cls, key, value)
-                del attrs[key]
-                continue
-
-            try:
-                new_value = value_mapping[value]
-            except KeyError:
-                new_value = value_cls(name=key, value=value)
-                value_mapping[value] = new_value
-                member_names.append(key)
-
-            member_mapping[key] = new_value
-            attrs[key] = new_value
-
-        attrs["_enum_value_map_"] = value_mapping
-        attrs["_enum_member_map_"] = member_mapping
-        attrs["_enum_member_names_"] = member_names
-        attrs["_enum_value_cls_"] = value_cls
-        actual_cls = super().__new__(cls, name, bases, attrs)
-        value_cls._actual_enum_cls_ = actual_cls  # type: ignore
-        return actual_cls
-
-    def __iter__(cls):
-        return (cls._enum_member_map_[name] for name in cls._enum_member_names_)
-
-    def __reversed__(cls):
-        return (cls._enum_member_map_[name] for name in reversed(cls._enum_member_names_))
-
-    def __len__(cls):
-        return len(cls._enum_member_names_)
-
-    def __repr__(cls):
-        return f"<enum {cls.__name__}>"
+class Enum(EnumBase):
+    """An :class:`enum.Enum` subclass that implements a missing value creation behavior if it is
+    not present in any of the members of it.
+    """
 
-    @property
-    def __members__(cls):
-        return types.MappingProxyType(cls._enum_member_map_)
-
-    def __call__(cls, value):
-        try:
-            return cls._enum_value_map_[value]
-        except (KeyError, TypeError) as e:
-            raise ValueError(f"{value!r} is not a valid {cls.__name__}") from e
-
-    def __getitem__(cls, key):
-        return cls._enum_member_map_[key]
-
-    def __setattr__(cls, name, value):
-        raise TypeError("Enums are immutable.")
-
-    def __delattr__(cls, attr):
-        raise TypeError("Enums are immutable")
-
-    def __instancecheck__(self, instance):
-        # isinstance(x, Y)
-        # -> __instancecheck__(Y, x)
-        try:
-            return instance._actual_enum_cls_ is self
-        except AttributeError:
-            return False
-
-
-if TYPE_CHECKING:
-    from enum import Enum
-else:
-
-    class Enum(metaclass=EnumMeta):
-        @classmethod
-        def try_value(cls, value):
-            try:
-                return cls._enum_value_map_[value]
-            except (KeyError, TypeError):
-                return value
+    @classmethod
+    def _missing_(cls, value: Any) -> Self:
+        name = f"unknown_{value}"
+        if name in cls.__members__:
+            return cls.__members__[name]
+
+        # this creates the new unknown value member
+        obj = object.__new__(cls)
+        obj._name_ = name
+        obj._value_ = value
+
+        # and adds it to the member mapping of this enum so we don't
+        # create a different enum member value each time
+        cls._member_map_[name] = obj
+        cls._value2member_map_[value] = obj
+        return obj
 
 
 class ChannelType(Enum):