Black-boxed nodes

[michalochman]

Add option to create black-boxed nodes which could be used to create effects, e.g. vibrato or delay.

[shyndman]

Why black box and not emphasize abstraction/reusability?

Because, I can imagine something more like a component system, where you define a sub-graph, indicate inputs and outputs, and give it a name. That then becomes a reusable node just like anything else...but it's never opaque. You can still jump in and continue to make changes to it.

[michalochman]

A subgraph is what I had in mind, sorry for not being clear. Opaqueness would come from a fact that an authors could "collapse" the subgraph to a single node visually and not concern themselves with what's inside.

One additional challenge is how to support different controls for internal values (knobs, sliders, toggles, selects etc) or how to expose these controls from inside. While supporting parameters (e. g. gain) should be free by using inputs, supporting non-parameter controls (e. g. oscillator type) would not be free.