Hi there, i found a nice article about a custom implementation of events by Duncan Booth here:
http://www.suttoncourtenay.org.uk/duncan/accu/pythonpatterns.html#observer The code is here: STEP 1) Define a Delegate Class 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]STEP 2) Define the Event Classclass 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) STEP 3) Use this logic in an object (ObjectA)class ClockTimer: def GetHour(self): return self._hour def GetMinute(self): return self._minute def GetSecond(self): return self._second TickEvent = Event() def OnTick(self): ClockTimer.TickEvent.call(self, self.GetHour(), self.GetMinute(), self.GetSecond()) def Tick(self): # update internal time-keeping state # ... self.OnTick() STEP 4) Subscribe the ObjectA Event and react...class DigitalClock(Widget): def __init__(self, clockTimer): self.__subject = clockTimer clockTimer.TickEvent += self.Update def close(self): self.__subject.TickEvent -= self.Update def Update(self, subject, hour, min, sec): self.displayedTime = (hour, min, sec) self.Draw() def Draw(self): # draw the digital clock I've tried to use it but i failed. From mypoint of view my event is never been fired and it seem that my event subscription is not accepted and my OnTick Event never raise to execute the Update method,i've made some changes to the original code.. jjust inserted a timer to have this event fired many times:class ClockTimer: _hour = 1 _minute = 1 _second = 1 _timer = Timers.timer(0) def __init__(self): self._timer.start(10) while 1: if(self._timer.isexpired()): self._hour = self._hour + 1 self._minute = self._minute +1 self._second = self._second +1 self.Tick() self._timer.start(10) def getHour(self): return self._hour def getMinutes(self): return self._minute def getSecond(self): return self._second TickEvent = Event() def OnTick(self): ClockTimer.TickEvent.call(self, self.getHour(), self.getMinutes(), self.getSecond()) def Tick(self): print "Tick in CLockTimer" self.OnTick()and a little modification to the object that uses this event:class DigitalClock(): clockTimer = ClockTimer() def __init__(self): clockTimer.TickEvent += self.update def close(self): self.__subject.TickEvent -= self.update def update(self, subject, hour, min, sec): print hour print min print secthe code is really eas as you can see... so in the main i added this simpleline of code...c = DigitalClock()but nothing really happen... i'm sure i'm going wrong somewhere.. but cant understand where...any Idea???I've tried to ask to Duncan directly by mail.. but the reported mail address is no more valid...Someone used this?? Someone uses an other way for events??? Regards,Gianmaria -- http://mail.python.org/mailman/listinfo/python-list
