Shows how multiple objects may subscribe to the same event

   


/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa

Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
 // Subscrib.cs -- Shows how multiple objects may subscribe to the same
//                event.
//
//                Compile this program with the following command line:
//                    C:>csc Subscrib.cs
using System;

namespace nsEvents
{
    public class Subscrib
    {
        // Declare an instance of the clsDelegate class. The event variable
        // is not static.
        static public clsDelegate dlg = new clsDelegate ();
        static public void Main ()
        {
            // Add clsMain to the event list
            dlg.DoEvent += new clsDelegate.StringHandler (ShowEvent);
            // Create subscribers for the event
            clsSubscriber sub = new clsSubscriber ();
            clsNextSubscriber sub2 = new clsNextSubscriber ();
            // Fire the event.
            dlg.FireEvent ("Fired from Main()");
        }
        static public void ShowEvent (string str)
        {
            Console.WriteLine ("Main handled event: " + str);
        }
    }


    public class clsDelegate
    {
        
        // Declare a delegate for the event
        public delegate void StringHandler (string str);
        
        // A variable to hold the delegate
        public event StringHandler DoEvent;
        
        // This method will trigger the event.
        public void FireEvent (string str)
        {
            if (DoEvent != null)
                DoEvent (str);
        }
    }

    public class clsSubscriber
    {
        public clsSubscriber ()
        {
            Subscrib.dlg.DoEvent +=
                         new clsDelegate.StringHandler (SubscribeEvent);
        }
        public void SubscribeEvent (string str)
        {
            Console.WriteLine ("Subscriber handled event: " + str);
        }
    }
    public class clsNextSubscriber
    {
        public clsNextSubscriber ()
        {
            Subscrib.dlg.DoEvent +=
                         new clsDelegate.StringHandler (SubscribeEvent);
        }
        public void SubscribeEvent (string str)
        {
            Console.WriteLine ("Next Subscriber handled event: " + str);
        }
    }
}