kundeng06 's List: scratch

class Delegate:
'''Handles a list of methods and functions
Usage:
d = Delegate()
d += function # Add function to end of delegate list
d(*args, **kw) # Call all functions, returns a list of results
d -= function # Removes last matching function from list
d -= object # Removes all methods of object from list
'''
def __init__(self):
self.__delegates = []

def __iadd__(self, callback):
self.__delegates.append(callback)
return self

def __isub__(self, callback):
# If callback is a class instance,
# remove all callbacks for that instance
self.__delegates = [ cb
for cb in self.__delegates
if getattr(cb, 'im_self', None) != callback]

# If callback is callable, remove the last
# matching callback
if callable(callback):
for i in range(len(self.__delegates)-1, -1, -1):
if self.__delegates[i] == callback:
del self.__delegates[i]
return self
return self

def __call__(self, *args, **kw):
return [ callback(*args, **kw)
for callback in self.__delegates]

class Event(property):
'''Class event notifier
Usage:
class C:
TheEvent = Event()
def OnTheEvent(self):
self.TheEvent(self, context)

instance = C()
instance.TheEvent += callback
instance.OnTheEvent()
instance.TheEvent -= callback
'''
def __init__(self):
self.attrName = attrName = "__Event_" + str(id(self))
def getEvent(subject):
if not hasattr(subject, attrName):
setattr(subject, attrName, Delegate())
return getattr(subject, attrName)
super(Event, self).__init__(getEvent)

def call(self, subject, *args, **kw):
if hasattr(subject, self.attrName):
getattr(subject, self.attrName)(subject, *args, **kw)