Les événements Compatible .Net

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/*
C#: The Complete Reference
by Herbert Schildt 
 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
 
// A .NET-compatible event. 
 
using System; 
 
// Derive a class from EventArgs.
class MyEventArgs : EventArgs {
  public int eventnum;
} 
 
// Declare a delegate for an event.
delegate void MyEventHandler(object source, MyEventArgs arg); 
 
// Declare an event class.
class MyEvent {
  static int count = 0; 
 
  public event MyEventHandler SomeEvent; 
 
  // This fires SomeEvent.
  public void OnSomeEvent() {
    MyEventArgs arg = new MyEventArgs(); 
 
    if(SomeEvent != null) {
      arg.eventnum = count++;
      SomeEvent(this, arg);
    }
  }
} 
 
class X {
  public void handler(object source, MyEventArgs arg) {
    Console.WriteLine("Event " + arg.eventnum +
                      " received by an X object.");
    Console.WriteLine("Source is " + source);
    Console.WriteLine();
  }
} 
 
class Y {
  public void handler(object source, MyEventArgs arg) {
    Console.WriteLine("Event " + arg.eventnum +
                      " received by a Y object.");
    Console.WriteLine("Source is " + source);
    Console.WriteLine();
  }
} 
 
public class EventDemo5 {
  public static void Main() {
    X ob1 = new X();
    Y ob2 = new Y();
    MyEvent evt = new MyEvent(); 
 
    // Add handler() to the event list.
    evt.SomeEvent += new MyEventHandler(ob1.handler);
    evt.SomeEvent += new MyEventHandler(ob2.handler); 
 
    // Fire the event.
    evt.OnSomeEvent();
    evt.OnSomeEvent();
  }
}