/*
 * A C# program that generates a custom event.
 * Modified from the .NET documentation
 *
 * Ben Bederson, February 20, 2002
 */

using System;

//Step 1. Class that defines data for the event
//
public class AlarmEventArgs : EventArgs {   
    private int nrings = 0;
    // Constructor.
    public AlarmEventArgs(int nrings) {
	this.nrings = nrings;
    }

    // Properties.
    public int NumRings { 
	get { return nrings; }
    }
}
   
//Step 2. Delegate declaration.
//
public delegate void AlarmEventHandler(object sender, AlarmEventArgs e);

// Class definition.
//
public class AlarmClock {
    //Step 3. The Alarm event is defined using the event keyword.
    //The type of Alarm is AlarmEventHandler.
    public event AlarmEventHandler Alarm;

    //
    //Step 4. The protected OnAlarm method raises the event by invoking 
    //the delegates. The sender is always this, the current instance of 
    //the class.
    //   
    protected virtual void OnAlarm(AlarmEventArgs e) 
    {
	if (Alarm != null) {
	    //Invokes the delegates.
	    Alarm(this, e); 
	}
    }

    public void ForceAlarm() {
	OnAlarm(new AlarmEventArgs(3));
    }
}

public class Test {
    static public void Main() {
	new Test();
    }

    public Test() {
	AlarmClock clock = new AlarmClock();
	clock.Alarm += new AlarmEventHandler(alarmHandler);

	clock.ForceAlarm();
    }

    void alarmHandler(object sender, AlarmEventArgs e) {
	Console.WriteLine("alarm!  " + e.NumRings + " rings");
    }
}