composition.py

class EffectCompose(EffectMeta):
    def __init__(cls, name, bases, dct):
        super().__init__(name, bases, dct)
        def compose(a,b,abort_on_fail=False):
            if not a:
                return b
            if abort_on_fail:
                def f(statecont, *args, **kwargs):
                    res = a(statecont)
                    if res.opstate:
                        return b(res)
            else:
                def f(statecont, *args, **kwargs):
                    return b(a(statecont))
            return f

        behaviors = dct["behaviors"]
        d = ""
        f = None
        for b in behaviors:
            f = compose(f, b)
            d += "\n{0}".format(b.__doc__)
        def call(self, state, *args, **kwargs):
            return f(state, *args, **kwargs)
        def init(self):
            pass
        cls.__init__ = init
        cls.__call__ = call
        cls.__doc__ = d