Observer Mania!!

Question

I have some classes that have lots of observers. Or I should say, lots of different types of observers. I have this question each time I add a new event. Should I use an interface for my observer architecture with my events in it, or should I use a simple properly event?
Right now I am about to add an event for when I add a "variant" to a connection. I am wondering if I should add this to a growing set of property events and filre an Property.VARIANT property event, or to an IConnectionEventListener. Also, when I make my own events, I dont know if I should have a "ConnectionEvent" object to pass out during the event notification!?
Any standard way to make these decisions, or is it arbitrary?

Answer 1

I tend to favor custom interfaces. PropertyChangeListeners are too open ended. if you add a new event to a custom listener interface, it's easy too see where you might potentially need to handle it. This is not so with PropertyChangeEvents.
I've recently used a generic parameter to define the Listener type for a hierarchy of even producers. This allows me to add different events to different producers without forcing every listener to handle an event that isn't relevant to them.
I hope that helps. If not ask your question again and I'll see if I can do better.