Clean up flag code significantly.

This also fixes the False setting bug.

discord/flags.py

@@ -29,7 +29,7 @@ __all__ = (
     'MessageFlags',
 )
 
-class _flag_descriptor:
+class flag_value:
     def __init__(self, func):
         self.flag = func(None)
         self.__doc__ = func.__doc__
@@ -40,19 +40,70 @@ class _flag_descriptor:
     def __set__(self, instance, value):
         instance._set_flag(self.flag, value)
 
-def fill_with_flags(cls):
-    cls.VALID_FLAGS = {
-        name: value.flag
-        for name, value in cls.__dict__.items()
-        if isinstance(value, _flag_descriptor)
-    }
+def fill_with_flags(*, inverted=False):
+    def decorator(cls):
+        cls.VALID_FLAGS = {
+            name: value.flag
+            for name, value in cls.__dict__.items()
+            if isinstance(value, flag_value)
+        }
+
+        if inverted:
+            max_bits = max(cls.VALID_FLAGS.values()).bit_length()
+            cls.DEFAULT_VALUE = -1 + (2 ** max_bits)
+        else:
+            cls.DEFAULT_VALUE = 0
+
+        return cls
+    return decorator
+
+# n.b. flags must inherit from this and use the decorator above
+class BaseFlags:
+    __slots__ = ('value',)
+
+    def __init__(self, **kwargs):
+        self.value = self.DEFAULT_VALUE
+        for key, value in kwargs.items():
+            if key not in self.VALID_FLAGS:
+                raise TypeError('%r is not a valid flag name.' % key)
+            setattr(self, key, value)
+
+    @classmethod
+    def _from_value(cls, value):
+        self = cls.__new__(cls)
+        self.value = value
+        return self
+
+    def __eq__(self, other):
+        return isinstance(other, self.__class__) and self.value == other.value
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __hash__(self):
+        return hash(self.value)
+
+    def __repr__(self):
+        return '<%s value=%s>' % (self.__class__.__name__, self.value)
 
-    max_bits = max(cls.VALID_FLAGS.values()).bit_length()
-    cls.ALL_OFF_VALUE = -1 + (2 ** max_bits)
-    return cls
+    def __iter__(self):
+        for name, value in self.__class__.__dict__.items():
+            if isinstance(value, flag_value):
+                yield (name, self._has_flag(value.flag))
+
+    def _has_flag(self, o):
+        return (self.value & o) == o
+
+    def _set_flag(self, o, toggle):
+        if toggle is True:
+            self.value |= o
+        elif toggle is False:
+            self.value &= ~o
+        else:
+            raise TypeError('Value to set for %s must be a bool.' % self.__class__.__name__)
 
-@fill_with_flags
-class SystemChannelFlags:
+@fill_with_flags(inverted=True)
+class SystemChannelFlags(BaseFlags):
     r"""Wraps up a Discord system channel flag value.
 
     Similar to :class:`Permissions`\, the properties provided are two way.
@@ -85,37 +136,7 @@ class SystemChannelFlags:
         representing the currently available flags. You should query
         flags via the properties rather than using this raw value.
     """
-    __slots__ = ('value',)
-
-    def __init__(self, **kwargs):
-        self.value = self.ALL_OFF_VALUE
-        for key, value in kwargs.items():
-            if key not in self.VALID_FLAGS:
-                raise TypeError('%r is not a valid flag name.' % key)
-            setattr(self, key, value)
-
-    @classmethod
-    def _from_value(cls, value):
-        self = cls.__new__(cls)
-        self.value = value
-        return self
-
-    def __eq__(self, other):
-        return isinstance(other, SystemChannelFlags) and self.value == other.value
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
-    def __hash__(self):
-        return hash(self.value)
-
-    def __repr__(self):
-        return '<SystemChannelFlags value=%s>' % self.value
-
-    def __iter__(self):
-        for name, value in self.__class__.__dict__.items():
-            if isinstance(value, _flag_descriptor):
-                yield (name, self._has_flag(value.flag))
+    __slots__ = ()
 
     # For some reason the flags for system channels are "inverted"
     # ergo, if they're set then it means "suppress" (off in the GUI toggle)
@@ -133,19 +154,19 @@ class SystemChannelFlags:
         else:
             raise TypeError('Value to set for SystemChannelFlags must be a bool.')
 
-    @_flag_descriptor
+    @flag_value
     def join_notifications(self):
         """:class:`bool`: Returns ``True`` if the system channel is used for member join notifications."""
         return 1
 
-    @_flag_descriptor
+    @flag_value
     def premium_subscriptions(self):
         """:class:`bool`: Returns ``True`` if the system channel is used for Nitro boosting notifications."""
         return 2
 
 
-@fill_with_flags
-class MessageFlags:
+@fill_with_flags()
+class MessageFlags(BaseFlags):
     r"""Wraps up a Discord Message flag value.
 
     See :class:`SystemChannelFlags`.
@@ -173,65 +194,24 @@ class MessageFlags:
         representing the currently available flags. You should query
         flags via the properties rather than using this raw value.
     """
-    __slots__ = ('value',)
+    __slots__ = ()
 
-    def __init__(self, **kwargs):
-        self.value = 0
-        for key, value in kwargs.items():
-            if key not in self.VALID_FLAGS:
-                raise TypeError('%r is not a valid flag name.' % key)
-            setattr(self, key, value)
-
-    @classmethod
-    def _from_value(cls, value):
-        self = cls.__new__(cls)
-        self.value = value
-        return self
-
-    def __eq__(self, other):
-        return isinstance(other, MessageFlags) and self.value == other.value
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
-    def __hash__(self):
-        return hash(self.value)
-
-    def __repr__(self):
-        return '<MessageFlags value=%s>' % self.value
-
-    def __iter__(self):
-        for name, value in self.__class__.__dict__.items():
-            if isinstance(value, _flag_descriptor):
-                yield (name, self._has_flag(value.flag))
-
-    def _has_flag(self, o):
-        return (self.value & o) == o
-
-    def _set_flag(self, o, toggle):
-        if toggle is True:
-            self.value |= o
-        elif toggle is False:
-            self.value &= o
-        else:
-            raise TypeError('Value to set for MessageFlags must be a bool.')
-
-    @_flag_descriptor
+    @flag_value
     def crossposted(self):
         """:class:`bool`: Returns ``True`` if the message is the original crossposted message."""
         return 1
 
-    @_flag_descriptor
+    @flag_value
     def is_crossposted(self):
         """:class:`bool`: Returns ``True`` if the message was crossposted from another channel."""
         return 2
 
-    @_flag_descriptor
+    @flag_value
     def suppress_embeds(self):
         """:class:`bool`: Returns ``True`` if the message's embeds have been suppressed."""
         return 4
-    
-    @_flag_descriptor
+
+    @flag_value
     def source_message_deleted(self):
         """:class:`bool`: Returns ``True`` if the source message for this crosspost has been deleted."""
         return 8