improvement: allow custom STT engines as plug-ins #612

[SoloVeniaASaludar]

Allow custom STT engines as plug-ins.

See #612 for details

[clusterfudge]

I might recommend something like the following:

class STTFactory(object):
    CLASSES = {
        "mycroft": MycroftSTT,
        "google": GoogleSTT,
        "wit": WITSTT,
        "ibm": IBMSTT
    }

    @staticmethod
    def register_stt(name, engine_class):
        # assert api signature
        # ...
        CLASSESS.put(name, engine_class)

    @staticmethod
    def create():
        config = ConfigurationManager.get().get("stt", {})
        module = config.get("module", "mycroft")
        clazz = STTFactory.CLASSES.get(module)
        return clazz()

And then we can avoid importlib, and the convention of splitting config strings to try to construct plugins.

[SoloVeniaASaludar]

Thanks for the comment.

Who will call "register_stt" ?

[clusterfudge]

I see the meat of your question :). I'm assuming you want something that's entirely config driven, as opposed to something that requires writing code to inject. I don't think there's a precedent for that in mycroft (aside from skills), so someone from the core team may want to chime in on what direction they see that going.