"""
Abstract Subject
=================
This module implements a general metaclass of the subject/publisher of information.
"""
# ============================================================================
# STANDARD IMPORTS
# ============================================================================
import abc
from .observer import AbsObserver
# ============================================================================
# CLASS AND DEFINITIONS
# ============================================================================
[docs]class AbsSubject(metaclass=abc.ABCMeta):
_channels = {}
[docs] @abc.abstractclassmethod
def attach(self, observer, channel, callback):
"""Attach a new observer"""
pass
[docs] @abc.abstractclassmethod
def detach(self, observer, channel):
"""Detach an existing observer"""
pass
[docs] @abc.abstractclassmethod
def dispatch(self, channel):
"""Notify all observers by calling update method"""
pass
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self._channels.clear()
