Feature request: @allowed_channels decorator similar to @allowed_users

[ghbacct]

Feature request:
To introduce a decorator @allowed_channels that takes a list of white-listed channels, similarly to the @allowed_users decorator.

Something similar to the following pseudocode:

def allowed_channels(*channels):
    """Decorator that limits the bot to the specified list of channels."""
    def plugin(func):
        def wrapper(message, *args, **kw):
            is_direct_message = message.is_direct_message()
            is_in_allowed_channel = message.get_channel_name() in channels
            if not is_direct_message and not is_in_allowed_channel:
                return message.reply(f'This bot can only be used inside the following channel(s): {", ".join(channels)}.')
            return func(message, *args, **kw)

        return wrapper

    return plugin

[ghbacct]

@attzonko thank you for the enhancement!

There's one issue however: using @allowed_channels prevents the plugin from being used in DMs.
Is that intentional? Seems to me like an edge case that just slipped by.

[attzonko]

Yes edge case indeed. DMs are uniquely named channels. Depending on how we want this enhancement to work, we can update the code to allow the plugin to work in DMs regardless of allowed_channels(), either way we should document the intent.