Address arbitration doesn't allow for a bus created with receive_own_messages=True setting

[grant-allan-ctct]

If the ElectronicControlUnit.connect function is called with the receive_own_messages value set to True, then

Received ADDRESS CLAIMED message with conflicting address

message will be seen over and over in the console window if:

• start() is called on the ControllerApplication instance, or if
• send_message(0x18EAFF00 + ca._device_address, extended_id=True, data=(0, 0xEE, 0, 0, 0, 0, 0, 0)) is called on the ECU.

When looking at the messages, the MessageListener code is not checking whether the incoming msg has is_rx value of True or False before passing the message along to the listeners, and consequently the outgoing address-claim message from the CA itself is interpreted as if another ECU on the bus is competing for the same address.

[grant-allan-ctct]

I have come up with a workaround for this behavior. I create a subclass of ElectronicControlUnit class, and add these three methods to it:

    def add_listener(self, listener):
        self._listeners.append(listener)
        if self._notifier is not None:
            self._notifier.add_listener(listener)

    def remove_listener(self, listener):
        self._listeners.remove(listener)
        if self._notifier is not None:
            self._notifier.remove_listener(listener)

    def substitute_message_listener(self, listener : MessageListener):
        # Remove any existing MessageListener first:
        for alreadyListening in self._listeners:
          if isinstance(alreadyListening, MessageListener):
            self.remove_listener(alreadyListening)
        self.add_listener(listener)  

and I also create a subclass of MessageListener which has the bug-fix in its on_message_received function, like this:

class CustomMessageListener(MessageListener):

    def on_message_received(self, msg : can.Message):
        if msg.is_rx:
            super().on_message_received(msg)

Finally, in my application code, after creating my ECU instance, I call the substitute_message_listener of my ECU, passing in an instance of CustomMessageListener.

[grant-allan-ctct]

My substitute_message_listener function in prior comment had a mistake - the same kind of mistake that's in our remove_timer function here where we are removing items while inside a for-loop that's cycling through that same list. I have changed my function to this instead now:

    def substitute_message_listener(self, listener : MessageListener):
        # Remove any existing MessageListener first:
        self._listeners[:] = [item for item in self._listeners if not isinstance(item, MessageListener)]
        self.add_listener(listener)    

which was inspired by this stackoverflow post.

(If someday we try to rework #42 we might be able to do something similar in the remove_timer function.)