What is the difference between TeamsActivityHandler and ActivityHandler?

Question

In most documentation you'll see:

class BotHandler(ActivityHandler):
    async def on_message_activity(self, turn_context: TurnContext):
        await turn_context.send_activity("Hello!")

However, some Python examples will use TeamsActivityHandler instead:

class BotHandler(TeamsActivityHandler):
    async def on_message_activity(self, turn_context: TurnContext):
        message = MessageFactory.text("first message")
        channel_id = teams_get_channel_id(turn_context.activity)

I've noticed that

1. When inheriting from TeamsActivityHandler, I can overload on_teams_channel_created() that gets called when a new channel is created.
2. When inheriting from ActivityHandler, I can overload on_members_added_activity() to greet new users (welcome message).

How can I use both at the same time?

Answer 1

I found the solution. If you inherit from TeamsActivityHandler you may override on_teams_members_added() instead.

This is rather counter intuitive because when you inherit from TeamsActivityHandler (which in turn inherits from TeamsActivity) you assume get the same functionality (i.e: be able to override the same function(s)). This does not seem to be the case due to the super() used here.

If you inherit from TeamsActivity you may override on_members_added_activity() as per usual.

Not sure if this is a bug or just weird design.