screen abstraction proposition for ZPUI

proposition.py

class MyApp:
    def __init__(self, o):
        # type: (AbstractScreen) -> None
        self.o = o
        self.my_loading_bar = LoadingBar(o)  # As an app developper I don't wanna know what the screens are !

    def on_start(self):
        self.my_loading_bar.activate()


# or procedural if you prefer ;)
# def init_app(i,o):
#     global my_loading_bar
#     my_loading_bar = Loadingbar(o)
#
# def callback():
#     my_loading_bar.activate()


class LoadingBar:

    def __new__(cls, o):
        # here we use __new__ instead of __init__ so we can return something else instead
        # of an instance of LoadingBar
        return cls.find_ui_matching_requirement(o)

    def activate(self):
        pass

    def find_ui_matching_requirement(self, o):
        has_requirement = bool(set(o.supported_modes) & set(ImageLoadingBar.requirements))
        if has_requirement:
            return ImageLoadingBar(o)

        has_requirement = bool(set(o.supported_modes) & set(TextLoadingBar.requirements))
        if has_requirement:
            return TextLoadingBar(o)


class ImageLoadingBar:
    requirements = ['pixel']

    def __init__(self, o):
        self.o = o

    def activate(self):
        pass  # todo : remove


class TextLoadingBar:
    requirements = ['char']

    def __init__(self, o):
        self.o = o

    def activate(self):
        pass  # todo : remove


class AbstractScreen:
    requirements = []
    def __init__(self):
        pass


class SomeBWScreen:
    def __init__(self):
        self.supported_modes = ['char', 'b&w', 'pixel']  # ... and more


class SomeCharacterScreen:
    def __init__(self):
        self.supported_modes = ['chars', 'pixel']  # ... and more