Can I make individual callbacks to handle each MQTT topic?

Question

I'm using the PubSubClient on some ESP-01 modules to make smart/connected devices around the house. I'm not super fond of the way all incoming messages get routed to the single callback. When I get a message, I have to parse the topic and deal with each topic in a switch statement. There's probably a better way to do this but I haven't thought of anything yet.

It would be nice if I could assign a separate callback for each subscribed topic. Right now I just have a list of strings, with the last item being "END", and I loop through subscribing to the items in the list until I hit END. That's fine, but I'd like to be able to dynamically load the topics from the network eventually, so I can't have a hard-coded list or switch statement.

Is there a way to do this? I understand that I'd need a callback for each potential topic but that's fine, I just don't know how to assign callbacks to the topics I'm subscribed to.

Answer 1

Short answer no, the library only takes a single callback, which is passed the topic of the incoming message as a parameter.

Longer answer, there is nothing to stop you implementing this yourself.

You just have a big if/else block in the callback function that just calls individual methods for each topic based on the topic value passed into the callback function.

What you've described wouldn't let you dynamically assign topics anyway, you'd still need a pre-defined function for each possible topic (or at least each possible action to take, that could be mapped to the required topic)