Delegates by Example Part 2

3/27/2017

using System;
/* This example illustrates building one delegate to call several functions in sequence
 * The final output of this example will be
 *
 * WriteOut method called
 * 2
 * WriteIn method called
 * 1
 * WriteIn method called
 * 0
 *
 * Notice that even though we pass 1 to the arguments of the delegate, the first iteration of
 * WriteIn recieves the value of 2. This is because WriteOut modified that value to 2.
 * Using this method, all functions share the same argument, thus if the first function modifies
 * it's value, it's modified for all the rest of the functions in the list.
 * This is very important in deciding whether to use the method in example1 or example2, as it
 * can significantly change the resulting output of the program.
 * (NOTE: This is not true on every compiler, test to find out)
 */
namespace DelegatesTutorial
{
  class Example2
  {
    // Declare the delegate to be used later, this sets the return type and expected parameters
    // for the delegate. All functions to be included must have the same return type and parameter list.
    delegate void MyDelegate(int number);
    public Example2()
    {
      // We'll create a single delegate from MyDelegate and assign WriteOut to it
      MyDelegate TheDelegate = new MyDelegate(WriteOut);
      // Now add WriteIn to the existing delegate
      TheDelegate += new MyDelegate(WriteIn);
      // Call the functions of the delegate
      TheDelegate(1);
      // Remove the WriteOut delegate
      TheDelegate -= new MyDelegate(WriteOut);
      // Call the functions of the delegate again.
      TheDelegate(1);
    }
    // These are the functions to be called by the delegate
    void WriteOut(int number)
    {
      Console.WriteLine("WriteOut method called");
      int i = ++number;
      Console.WriteLine(i.ToString());
    }
    void WriteIn(int number)
    {
      Console.WriteLine("WriteIn method called");
      int i = --number;
      Console.WriteLine(i.ToString());
    }
  }
}

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