using System;

//using System.Collections.Generic;

//using System.Text;

​

namespace Event_Example

{

  // First we have to define a delegate that acts as a signature for the

  // function that is ultimately called when the event is triggered.

  // You will notice that the second parameter is of MyEventArgs type.

  // This object will contain information about the triggered event.

​

  public delegate void MyEventHandler(object source, MyEventArgs e);

​

  // This is a class which describes the event to the class that recieves it.

  // An EventArgs class must always derive from System.EventArgs.

​

  public class MyEventArgs : EventArgs

  {

    private string EventInfo;

​

    public MyEventArgs(string Text) {

      EventInfo = Text;

    }

​

    public string GetInfo() {

      return EventInfo;

    }

  }

​

  // This next class is the one which contains an event and triggers it

  // once an action is performed. For example, lets trigger this event

  // once a variable is incremented over a particular value. Notice the

  // event uses the MyEventHandler delegate to create a signature

  // for the called function.

​

  public class MyClass

  {

    public event MyEventHandler OnMaximum;

​

    private int i;

    private int Maximum = 10;

​

    public int MyValue

    {

      get { return i; }

      set

      {

        if(value <= Maximum) {

          i = value;

        }

        else {

          // To make sure we only trigger the event if a handler is present

          // we check the event to make sure it's not null.

          if(OnMaximum != null) {

            OnMaximum(this, new MyEventArgs("You've entered " +

              value.ToString() +

              ", but the maximum is " +

              Maximum.ToString()));

          }

        }

      }

    }

  }

​

  public class Program

  {

    //This is the actual method that will be assigned to the event handler

    //within the above class. This is where we perform an action once the

    //event has been triggered.

​

    static void MaximumReached(object source, MyEventArgs e) {

      Console.WriteLine(e.GetInfo());

    }

​

    public static void Main(string[] args) {

      //Now lets test the event contained in the above class.

      MyClass MyObject = new MyClass();

      MyObject.OnMaximum += new MyEventHandler(MaximumReached);

      for(int x = 0; x <= 15; x++) {

        MyObject.MyValue = x;

      }

      Console.ReadLine();

    }

  }

}