baseimage-tutorial-framework/lib/tfw/internals/callback_mixin.py

from functools import partial

from .lazy import lazy_property


class CallbackMixin:
    @lazy_property
    def _callbacks(self):
        # pylint: disable=no-self-use
        return []

    def subscribe_callback(self, callback, *args, **kwargs):
        """
        Subscribe a callable to invoke once an event is triggered.
        :param callback: callable to be executed on events
        :param args: arguments passed to callable
        :param kwargs: kwargs passed to callable
        """
        fun = partial(callback, *args, **kwargs)
        self._callbacks.append(fun)

    def subscribe_callbacks(self, *callbacks):
        """
        Subscribe a list of callbacks to incoke once an event is triggered.
        :param callbacks: callbacks to be subscribed
        """
        for callback in callbacks:
            self.subscribe_callback(callback)

    def unsubscribe_callback(self, callback):
        self._callbacks.remove(callback)

    def _execute_callbacks(self, *args, **kwargs):
        for callback in self._callbacks:
            callback(*args, **kwargs)