Declare Member Function that accept Functor

[kempofighter]

I'm not sure that you want a functor here. I have usually seen multiple inheritance as a way of solving this. Create an interface class called EventHandler which provides a pure virtual function called processEvent. All observers must inherit from this interface and register with an event supplier. Of course it is possible that it is the only base class needed for some. The point is that an observer could implement any number of interfaces with multiple inheritance. In your case the Observer class could be the event handler and the call back function name can be whatever you wish. You can use dynamic_cast to ensure that the event handler objects implement the observer interface. I'm not sure what your myForeach is supposed to be. If you have a container of pointers you can use std::for_each and create a functor that calls processEvent on each object since you have a container of observers that provides iterator support.