ch5_7.cs

《c#技术内幕代码》

using System;

public class EventHandler1Class
{
   public static void HandleEvent1(string s)
   {
      Console.WriteLine("EventHandler1::HandleEvent1 called [{0}]", s);
   }
}

public class EventHandler2Class
{
   public static void HandleEvent1(string s)
   {
      Console.WriteLine("EventHandler2::HandleEvent1 called [{0}]", s);
   }
}

public class EventClass
{
   public delegate void OnEventFired( string s );
   
   private string fS;
   public OnEventFired evf = null;
   
   public EventClass( string s )
   {
      fS = s;
      OnFireEvent();
   }
   public void setString(string s)
   {
      fS = s;
      OnFireEvent();
   }
   
   private void OnFireEvent()
   {
      // Just fire the event
      if ( evf != null )
         evf( fS );
   }
   
   public void CallAllEventHandlers( string s )
   {
      if ( evf == null )
         return;
	 
      Delegate[] list = evf.GetInvocationList();
      for ( int i=0; i<list.Length; ++i )
      {
         OnEventFired oef = (OnEventFired)list[i];
         oef( s );
      }
   }
}

public class CH5_7
{
   public static void Main()
   {
      // Create the event handlers
      EventClass.OnEventFired ev1 = new 
         EventClass.OnEventFired( EventHandler1Class.HandleEvent1 );
      EventClass.OnEventFired ev2 = new 
         EventClass.OnEventFired( EventHandler2Class.HandleEvent1 );

      // Now, create an instance of the class
      EventClass e = new EventClass("Hello world");
      
      // Setup the handler
      e.evf = (EventClass.OnEventFired)Delegate.Combine( ev1, ev2 );
      
      // Change something so that it is called
      e.setString("Hello!");
      
      // Now, call all the handlers
      e.CallAllEventHandlers("Goodbye!");
      	 
   }

}