Keep track of Emoji instances myself.

WeakValueDictionary cleans up too late and brings too little benefit.
Also clean up the state when the first READY is encountered for
AutoShardedClient and when any READY is encountered in regular Client.

discord/emoji.py

@@ -73,7 +73,7 @@ class Emoji(Hashable):
         A list of :class:`Role` that is allowed to use this emoji. If roles is empty,
         the emoji is unrestricted.
     """
-    __slots__ = ('require_colons', 'managed', 'id', 'name', 'roles', 'guild', '_state', '__weakref__')
+    __slots__ = ('require_colons', 'managed', 'id', 'name', 'roles', 'guild', '_state')
 
     def __init__(self, *, guild, state, data):
         self.guild = guild

discord/state.py

@@ -70,7 +70,7 @@ class ConnectionState:
     def clear(self):
         self.user = None
         self._users = weakref.WeakValueDictionary()
-        self._emojis = weakref.WeakValueDictionary()
+        self._emojis = {}
         self._calls = {}
         self._guilds = {}
         self._voice_clients = {}
@@ -157,6 +157,11 @@ class ConnectionState:
     def _remove_guild(self, guild):
         self._guilds.pop(guild.id, None)
 
+        for emoji in guild.emojis:
+            self._emojis.pop(emoji.id, None)
+
+        del guild
+
     @property
     def emojis(self):
         return list(self._emojis.values())
@@ -249,6 +254,7 @@ class ConnectionState:
 
     def parse_ready(self, data):
         self._ready_state = ReadyState(launch=asyncio.Event(), guilds=[])
+        self.clear()
         self.user = ClientUser(state=self, data=data['user'])
 
         guilds = self._ready_state.guilds
@@ -760,7 +766,6 @@ class ConnectionState:
 class AutoShardedConnectionState(ConnectionState):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self._ready_state = ReadyState(launch=asyncio.Event(), guilds=[])
         self._ready_task = None
 
     @asyncio.coroutine
@@ -817,6 +822,7 @@ class AutoShardedConnectionState(ConnectionState):
     def parse_ready(self, data):
         if not hasattr(self, '_ready_state'):
             self._ready_state = ReadyState(launch=asyncio.Event(), guilds=[])
+            self.clear()
 
         self.user = ClientUser(state=self, data=data['user'])