Add ability to pass arbitrary keys engine.setValue and engine.setParameter

[christophehenry]

Add ability to pass arbitrary keys engine.setValue and engine.setParameter

[Swiftb0y]

This has been requested often, but it has lots of implications that we want to avoid. Reactive programming makes definitely sense, but it would be better to implement natively by writing mappings in QML (currently not possible, but wanted).

[Swiftb0y]

The reactive programming that Mixxx controls offers just makes the code cleaner and I was interested in improving Mixxx anyway.

I agree, but connections to COs is not the solution. For now, regular imperative OO-oriented programming suffices for controller mappings (I recommend you take a look at ComponentJS).

If you want to improve mixxx controller scripting, I recommend you take a look at some small features such as the registering input handlers project you already discovered. Those will likely take a medium amount of code (300-500 SLOC I'm guessing) and would already help a lot in making the mapping system better.

[christophehenry]

Is it related in some way to the Registering MIDI Input Handlers From Javascript topic in some way?

[Swiftb0y]

Not really, that is separate. It's related rather to the fact that arbitrary COs for controller mappings (which have been requested previously for inter-mapping communication) are bound to introduce compatibility issues between mappings.
(also just fyi since you're currently learning the controller mapping system, prefer to use engine.makeConnection over engine.connectControl, the latter has been deprecated for quite a while).

[christophehenry]

COs? Ok, so how hard would that be? Where should I start if I wanted to work on this?

[Swiftb0y]

COs?

Sorry for glossing over that. That short for what we call "Control Objects" and its the [group],key API you're interacting with via the engine.set* calls.

Ok, so how hard would that be?

Medium I'd guess. Like 50 SLOC. But as I said, that is not a good solution and I would be inclined to reject such a PR currently.

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I want to help you, so lets get back to the drawing board. What is your current usecase? I assume the break example you posted above?

[christophehenry]

Some of it, yes. The DN-S3700 implements several features like this one, involving multiple components interacting with one another. In the abstract, this is entirely solvable with states in JS variables. Especially now that the JS engine supports classes. The reactive programming that Mixxx controls offers just makes the code cleaner and I was interested in improving Mixxx anyway.