your function wrapper is just a Patch without any args.
... with the specific characteristic that it should never be rendered into a separate synth, just embedded into the synthdef.
With a little more work, it would be possible to cache the UGens so that multiple references to the same argument in the Instr would share the same UGen mini-graph.
I don't get why it would be a \noncontrol
surely it has an audio rate output
Again, the intent is not to patch an audio or control input. It's just to embed the UGens. For that, no synth control should be created and noncontrol is the way to be sure of that.