feat!: one time event listeners (#1957)

Signed-off-by: Om <92863779+Om1609@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: VincentRPS <vincentbusiness55@gmail.com>
Co-authored-by: Lulalaby <lala@pycord.dev>

CHANGELOG.md

@@ -19,8 +19,15 @@ These changes are available on the `master` branch, but have not yet been releas
   ([#1940](https://github.com/Pycord-Development/pycord/pull/1940))
 - Added support for text-related features in `StageChannel`.
   ([#1936](https://github.com/Pycord-Development/pycord/pull/1936))
+- Added support for one-time event listeners in `@client.listen()`.
+  ([#1957](https://github.com/Pycord-Development/pycord/pull/1957))
 - Added `current_page` argument to Paginator.update()
-  ([#1983](https://github.com/Pycord-Development/pycord/pull/1983))
+  ([#1983](https://github.com/Pycord-Development/pycord/pull/1983)
+
+### Removed
+
+- Removed `@client.once()` in favour of `@client.listen(once=True)`
+  ([#1957](https://github.com/Pycord-Development/pycord/pull/1957))
 
 ## [2.4.1] - 2023-03-20
 

discord/client.py

@@ -435,9 +435,19 @@ def dispatch(self, event: str, *args: Any, **kwargs: Any) -> None:
         else:
             self._schedule_event(coro, method, *args, **kwargs)
 
+        # collect the once listeners as removing them from the list
+        # while iterating over it causes issues
+        once_listeners = []
+
         # Schedule additional handlers registered with @listen
         for coro in self._event_handlers.get(method, []):
             self._schedule_event(coro, method, *args, **kwargs)
+            if coro._once:
+                once_listeners.append(coro)
+
+        # remove the once listeners
+        for coro in once_listeners:
+            self._event_handlers[method].remove(coro)
 
     async def on_error(self, event_method: str, *args: Any, **kwargs: Any) -> None:
         """|coro|
@@ -1204,7 +1214,7 @@ def remove_listener(self, func: Coro, name: str = MISSING) -> None:
             except ValueError:
                 pass
 
-    def listen(self, name: str = MISSING) -> Callable[[Coro], Coro]:
+    def listen(self, name: str = MISSING, once: bool = False) -> Callable[[Coro], Coro]:
         """A decorator that registers another function as an external
         event listener. Basically this allows you to listen to multiple
         events from different places e.g. such as :func:`.on_ready`
@@ -1233,6 +1243,11 @@ async def on_message(message):
             async def my_message(message):
                 print('two')
 
+            # listen to the first event only
+            @client.listen('on_ready', once=True)
+            async def on_ready():
+                print('ready!')
+
         Would print one and two in an unspecified order.
         """
 
@@ -1241,6 +1256,7 @@ def decorator(func: Coro) -> Coro:
             if name == "on_application_command_error":
                 return self.event(func)
 
+            func._once = once
             self.add_listener(func, name)
             return func
 
@@ -1286,64 +1302,6 @@ async def on_ready():
         _log.debug("%s has successfully been registered as an event", coro.__name__)
         return coro
 
-    def once(
-        self, name: str = MISSING, check: Callable[..., bool] | None = None
-    ) -> Coro:
-        """A decorator that registers an event to listen to only once.
-
-        You can find more info about the events on the :ref:`documentation below <discord-api-events>`.
-
-        The events must be a :ref:`coroutine <coroutine>`, if not, :exc:`TypeError` is raised.
-
-        Parameters
-        ----------
-        name: :class:`str`
-            The name of the event we want to listen to. This is passed to
-            :py:meth:`~discord.Client.wait_for`. Defaults to ``func.__name__``.
-        check: Optional[Callable[..., :class:`bool`]]
-            A predicate to check what to wait for. The arguments must meet the
-            parameters of the event being waited for.
-
-        Raises
-        ------
-        TypeError
-            The coroutine passed is not actually a coroutine.
-
-        Example
-        -------
-
-        .. code-block:: python3
-
-            @client.once()
-            async def ready():
-                print('Ready!')
-        """
-
-        def decorator(func: Coro) -> Coro:
-            if not asyncio.iscoroutinefunction(func):
-                raise TypeError("event registered must be a coroutine function")
-
-            async def wrapped() -> None:
-                nonlocal name
-                nonlocal check
-
-                name = func.__name__ if name is MISSING else name
-
-                args = await self.wait_for(name, check=check)
-
-                arg_len = func.__code__.co_argcount
-                if arg_len == 0 and args is None:
-                    await func()
-                elif arg_len == 1:
-                    await func(args)
-                else:
-                    await func(*args)
-
-            self.loop.create_task(wrapped())
-            return func
-
-        return decorator
-
     async def change_presence(
         self,
         *,

docs/api/clients.rst

@@ -10,7 +10,7 @@ Bots
 .. autoclass:: Bot
     :members:
     :inherited-members:
-    :exclude-members: command, event, message_command, slash_command, user_command, listen, once
+    :exclude-members: command, event, message_command, slash_command, user_command, listen
 
     .. automethod:: Bot.command(**kwargs)
         :decorator:
@@ -27,10 +27,7 @@ Bots
     .. automethod:: Bot.user_command(**kwargs)
         :decorator:
 
-    .. automethod:: Bot.listen(name=None)
-        :decorator:
-
-    .. automethod:: Bot.once(name=None, check=None)
+    .. automethod:: Bot.listen(name=None, once=False)
         :decorator:
 
 .. attributetable:: AutoShardedBot
@@ -44,15 +41,15 @@ Clients
 .. attributetable:: Client
 .. autoclass:: Client
     :members:
-    :exclude-members: fetch_guilds, event, once
+    :exclude-members: fetch_guilds, event, listen
 
     .. automethod:: Client.event()
         :decorator:
 
     .. automethod:: Client.fetch_guilds
         :async-for:
 
-    .. automethod:: Client.once(name=None, check=None)
+    .. automethod:: Client.listen(name=None, once=False)
         :decorator:
 
 .. attributetable:: AutoShardedClient

docs/ext/commands/api.rst

@@ -23,7 +23,7 @@ Bot
 .. autoclass:: discord.ext.commands.Bot
     :members:
     :inherited-members:
-    :exclude-members: after_invoke, before_invoke, check, check_once, command, event, group, listen, once
+    :exclude-members: after_invoke, before_invoke, check, check_once, command, event, group, listen
 
     .. automethod:: Bot.after_invoke()
         :decorator:
@@ -46,10 +46,7 @@ Bot
     .. automethod:: Bot.group(*args, **kwargs)
         :decorator:
 
-    .. automethod:: Bot.listen(name=None)
-        :decorator:
-
-    .. automethod:: Bot.once(name=None, check=None)
+    .. automethod:: Bot.listen(name=None, once=False)
         :decorator:
 
 AutoShardedBot