public void Detach()
 {
     _list.Changed -= new ChangedEventHandler(ListChanged);
     _list = null;
 }
        static void Main()
        {
            ListWithCahngedEvent list = new ListWithCahngedEvent();

            EventListener listener = new EventListener(list);
            list.Add("obj1");
            list.Add("obj2");
        }
 public EventListener(ListWithCahngedEvent list)
 {
     _list = list;
     _list.Changed += new ChangedEventHandler(ListChanged);
 }