You can never avoid observers being removed while iterating. The observer can even be removed WHILE you are trying to call its notify() function. Therefore I suppose you need a try/catch mechanism. The lock is to ensure observerset is not changedd while copying the set of observers

lock(observers) set<Observer> os = observers.copy(); unlock(observers) for (Observer o: os) { try { o.notify() } catch (Exception e) { print "notification of "+o+"failed:"+e } } 

You can never avoid observers being removed while iterating.

The observer can even be removed WHILE you are trying to call its notify() function.

Therefore I suppose you need a try/catch mechanism.

The lock is to ensure observerset is not changedd while copying the set of observers

 lock(observers)  set<Observer> os = observers.copy();  unlock(observers)  for (Observer o: os) {   try { o.notify() }   catch (Exception e) {   print "notification of "+o+"failed:"+e   }  } 

You can never avoid observers being removed while iterating. The observer can even be removed WHILE you are trying to call its notify() function. Therefore I suppose you need a try/catch mechanism. The lock is to ensure observerset is not changedd while copying the set of observers

lock(observers) set os = observers.copy(); unlock(observers) for (Observer o: os) { try { o.notify() } catch (Exception e) { print "notification of "+o+"failed:"+e } }

You can never avoid observers being removed while iterating. The observer can even be removed WHILE you are trying to call its notify() function. Therefore I suppose you need a try/catch mechanism. The lock is to ensure observerset is not changedd while copying the set of observers

lock(observers) set<Observer> os = observers.copy(); unlock(observers) for (Observer o: os) { try { o.notify() } catch (Exception e) { print "notification of "+o+"failed:"+e } }