This is something I wanted to request for a while, and now with the mutlichannel connections it seems to be the right time to do this. This is also something that works in MAX (though I am not sure how it is managed in multichannel signals).
In MAX you have inlet/outlet objects that deal with both messages and a subpatch can send on a single connection both audio and control messages. MAX also has the [typeroute~] object that can split audio signal and control messages, which can be used in this case.
We already have half of the stuff working in Pd. The [inlet~] object already splits signal and control data with the 'fwd' argument. What we miss is the ability of [outlet~] also accept and send this through a single audio connection.
Use cases? This is really useful for a "modular like" system, with abstractions that work like modules with visual controls (GOP) connected to each other. I am designing a system like this now, inspired by euro-rack synth modules by the way. I wouldn't like to extend this discussion so much and bore you people with technical details of this project. It really seems like a great convenience that people would like and I bet others will come up with more use cases and special cases where this really saves the day.
For my purpose, what we have to do now is create more outlets / inlets and connect them, or use global sends/receives. I have an external that gets '$0' of a parent patch which also helps, but I think using this makes things easier and more powerful. I would have the liberty to design more functional modules.
This seems especially useful with multichannel connections, where we could also send control parameters for a specific channel, which can be retrieved inside [clone] with our already existing [inlet~ fwd] configuration.
What do you say?
cheers