Delegates And Events : delegate Event « Language Basics « C# / C Sharp

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C# / C Sharp » Language Basics » delegate EventScreenshots 
Delegates And Events
Delegates And Events

/*
Learning C# 
by Jesse Liberty

Publisher: O'Reilly 
ISBN: 0596003765
*/
 using System;

 namespace DelegatesAndEvents
 {
     public enum comparison
     {
         theFirstComesFirst = 1,
         theSecondComesFirst = 2
     }

     // A simple collection to hold two items
     class Pair
     {
         // Private array to hold the two objects
         private object[] thePair = new object[2];

         // The delegate declaration
         public delegate comparison
             WhichIsFirst(object obj1, object obj2);

         // Passed in constructor takes two objects,
         // added in order received
         public Pair(
             object firstObject,
             object secondObject)
         {
             thePair[0= firstObject;
             thePair[1= secondObject;
         }

         // Public method that orders the
         // two objects by whatever criteria the objects like!
         public void Sort(
             WhichIsFirst theDelegatedFunc)
         {
             if (theDelegatedFunc(thePair[0],thePair[1])
                 == comparison.theSecondComesFirst)
             {
                 object temp = thePair[0];
                 thePair[0= thePair[1];
                 thePair[1= temp;
             }
         }

         // Public method that orders the
         // two objects by the reverse of whatever criteria the
         // objects likes!
         public void ReverseSort(
             WhichIsFirst theDelegatedFunc)
         {
             if (theDelegatedFunc(thePair[0],thePair[1]) ==
                 comparison.theFirstComesFirst)
             {
                 object temp = thePair[0];
                 thePair[0= thePair[1];
                 thePair[1= temp;
             }
         }

         // Ask the two objects to give their string value
         public override string ToString()
         {
             return thePair[0].ToString() ", "
                 + thePair[1].ToString();
         }
     }

     class Dog
     {
         private int weight;

         public Dog(int weight)
         {
             this.weight=weight;
         }

         // dogs are sorted by weight
         public static comparison WhichDogComesFirst(
             Object o1, Object o2)
         {
             Dog d1 = (Dogo1;
             Dog d2 = (Dogo2;
             return d1.weight > d2.weight ?
                 comparison.theSecondComesFirst :
                 comparison.theFirstComesFirst;
         }
         public override string ToString()
         {
             return weight.ToString();
         }
     }

     class Student
     {
         private string name;
         public Student(string name)
         {
             this.name = name;
         }

         // Students are sorted alphabetically
         public static comparison
             WhichStudentComesFirst(Object o1, Object o2)
         {
             Student s1 = (Studento1;
             Student s2 = (Studento2;
             return (String.Compare(s1.name, s2.name?
                 comparison.theFirstComesFirst :
                 comparison.theSecondComesFirst);
         }

         public override string ToString()
         {
             return name;
         }
     }

    public class TesterDelegatesAndEvents11
    {
       public void Run()
       {
           // Create two students and two dogs
           // and add them to Pair objects
           Student Jesse = new Student("Jesse");
           Student Stacey = new Student ("Stacey");
           Dog Milo = new Dog(65);
           Dog Fred = new Dog(12);

           Pair studentPair = new Pair(Jesse,Stacey);
           Pair dogPair = new Pair(Milo, Fred);
           Console.WriteLine("studentPair\t\t\t: {0}",
               studentPair.ToString());
           Console.WriteLine("dogPair\t\t\t\t: {0}",
               dogPair.ToString());

           // Instantiate the delegates
           Pair.WhichIsFirst  theStudentDelegate =
               new Pair.WhichIsFirst(
               Student.WhichStudentComesFirst);

           Pair.WhichIsFirst theDogDelegate =
               new Pair.WhichIsFirst(
               Dog.WhichDogComesFirst);

           // Sort using the delegates
           studentPair.Sort(theStudentDelegate);
           Console.WriteLine("After Sort studentPair\t\t: {0}",
               studentPair.ToString());
           studentPair.ReverseSort(theStudentDelegate);
           Console.WriteLine("After ReverseSort studentPair\t: {0}",
               studentPair.ToString());

           dogPair.Sort(theDogDelegate);
           Console.WriteLine("After Sort dogPair\t\t: {0}",
               dogPair.ToString());
           dogPair.ReverseSort(theDogDelegate);
           Console.WriteLine("After ReverseSort dogPair\t: {0}",
               dogPair.ToString());
       }

       static void Main()
       {
          TesterDelegatesAndEvents11 t = new TesterDelegatesAndEvents11();
          t.Run();
       }
    }
 }

           
       
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5.Create a custom means of managing the event invocation listCreate a custom means of managing the event invocation list
6.Use the bult-in EventHandler delegateUse the bult-in EventHandler delegate
7.Use delegate: eventUse delegate: event
8.Delegate and event hierarchyDelegate and event hierarchy
9.Events:Add and Remove FunctionsEvents:Add and Remove Functions
10.Events:Add and Remove Functions 2Events:Add and Remove Functions 2
11.Events: Custom Add and RemoveEvents: Custom Add and Remove
12.Delegates And Events 2Delegates And Events 2
13.Chaining events.
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