Demonstrates combining and removing delegates to create new delegates

   

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

Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/

// DlgOps.cs -- demonstrates combining and removing delegates to create
//              new delegates.
//
//              Compile this program with the following command line:
//                  C:>csc DlgOps.cs
using System;

namespace nsDelegates
{
    public class DelegatesSample
    {
        public delegate void MathHandler (double val);

        static public void Main ()
        {
            DelegatesSample main = new DelegatesSample ();
            MathHandler dlg1, dlg2, dlg3;
            dlg1 = new MathHandler (main.TheSquareRoot);
            dlg2 = new MathHandler (main.TheSquare);
            dlg3 = new MathHandler (main.TheCube);
// Combine the delegates so you can execute all three at one on one value
            MathHandler dlgCombo = dlg1 + dlg2 + dlg3;
            Console.WriteLine ("Executing the combined delegate");
            dlgCombo (42);
// Now remove the second delegate
            MathHandler dlgMinus = dlgCombo - dlg2;
            Console.WriteLine ("
Executing the delegate with the second removed");
            dlgMinus (42);
// Show that the individual delegates are stil available
// Execute the delegates one at a time using different values
            Console.WriteLine ("
Execute the delegates individually:");
            dlg1 (64);
            dlg2 (12);
            dlg3 (4);
        }
        public void TheSquareRoot (double val)
        {
            Console.WriteLine ("The square root of " + val + " is " + Math.Sqrt (val));
        }
        public void TheSquare (double val)
        {
            Console.WriteLine ("The square of " + val + " is " + val * val);
        }
        public void TheCube (double val)
        {
            Console.WriteLine ("The cube of " + val + " is " + val * val * val);
        }
    }
}