fix typing in add_listener and remove_listener

[tamenol]

Use the union to typecheck these functions

[codecov]

Codecov Report

Merging #1335 (d431a3a) into develop (cb3d4dc) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #1335      +/-   ##
===========================================
+ Coverage    65.92%   65.99%   +0.06%     
===========================================
  Files           86       86              
  Lines         8955     8958       +3     
===========================================
+ Hits          5904     5912       +8     
+ Misses        3051     3046       -5     

[tamenol]

Declaration of Listener

python-can/can/notifier.py

Line 45 in c7ba84a

self.listeners: List[MessageRecipient] = list(listeners)

[zariiii9003]

Thank you. Since the notifier accepts coroutines, could you also add the Awaitable in the MessageRecipient definition?

MessageRecipient = Union[Listener, Callable[[Message], Union[Awaitable[None], None]]]

Then we can also remove the cast in

    def _on_message_received(self, msg: Message) -> None:
        for callback in self.listeners:
            res = cast(Union[None, Optional[Awaitable[Any]]], callback(msg))
            if res is not None and self._loop is not None and asyncio.iscoroutine(res):
                # Schedule coroutine
                self._loop.create_task(res)

[tamenol]

Thank you. Since the notifier accepts coroutines, could you also add the Awaitable in the MessageRecipient definition?

MessageRecipient = Union[Listener, Callable[[Message], Union[Awaitable[None], None]]]

Then we can also remove the cast in

    def _on_message_received(self, msg: Message) -> None:
        for callback in self.listeners:
            res = cast(Union[None, Optional[Awaitable[Any]]], callback(msg))
            if res is not None and self._loop is not None and asyncio.iscoroutine(res):
                # Schedule coroutine
                self._loop.create_task(res)

Done :)

[zariiii9003]

Pylint complains about unused imports now. I will merge once that's fixed.

[tamenol]

Pylint complains about unused imports now. I will merge once that's fixed.

Aha, I see. Will fix it. Still learning how to contribute.

Also for the if statement in _on_message_received, I use the walrus operator or leave as is?

    def _on_message_received(self, msg: Message) -> None:
        for callback in self.listeners:
            res = callback(msg)
            if res is not None and self._loop is not None and asyncio.iscoroutine(res):
                # Schedule coroutine
                self._loop.create_task(res)

    def _on_message_received(self, msg: Message) -> None:
        for callback in self.listeners:
            if (res := callback(msg)) is not None and self._loop is not None and asyncio.iscoroutine(res):
                # Schedule coroutine
                self._loop.create_task(res)

[zariiii9003]

The walrus operator would fail in python 3.7