Csharp/C Sharp/Generics/Generic delegate

a generic delegate being initialized with a normal method

<source lang="csharp"> using System; public delegate void DelegateClass<T>(T data); public class Starter {

   public static void Main() {
       DelegateClass<string> del = MethodA;
       del("data");
   }
   public static void MethodA(string data) {
       Console.WriteLine("MethodA ({0})", data);
   }

}

</source>

A simple generic delegate

<source lang="csharp"> using System; // Declare a generic delegate. delegate T GenericDelegate<T>(T v); class GenDelegateDemo {

 static int sum(int v) {
   int result = 0;
   for(int i=v; i>0; i--)
     result += i;
   return result;
 }
 static string reflect(string str) {
   string result = "";
   foreach(char ch in str)
     result = ch + result;
   return result;
 }
 public static void Main() {
   GenericDelegate<int> intDel = sum;
   Console.WriteLine(intDel(3));
   GenericDelegate<string> strDel = reflect;
   Console.WriteLine(strDel("Hello"));
 }

}

      </source>

Convert event to use generic delegate

<source lang="csharp"> /* Example code from

Chapter 18 - Generics C# 2.0: The Complete Reference, Second Edition by Herbert Schildt McGraw-Hill/Osborne ? 2006

• /

using System; class MyEventArgs : EventArgs {

 public int eventnum;

} delegate void MyEventHandler<T, V>(T source, V args); class MyEvent {

 static int count = 0;
 public event MyEventHandler<MyEvent, MyEventArgs> SomeEvent;
 public void OnSomeEvent() {
   MyEventArgs arg = new MyEventArgs();
   if(SomeEvent != null) {
     arg.eventnum = count++;
     SomeEvent(this, arg);
   }
 }

} class X {

 public void handler<T, V>(T source, V arg) where V : MyEventArgs {
   Console.WriteLine("Event " + arg.eventnum + " received by an X object.");
   Console.WriteLine("Source is " + source);
   Console.WriteLine();
 }

} class Y {

 public void handler<T,V>(T source, V arg) where V : MyEventArgs {
   Console.WriteLine("Event " + arg.eventnum + " received by a Y object.");
   Console.WriteLine("Source is " + source);
   Console.WriteLine();
 }

} class Test {

 public static void Main() {
   X ob1 = new X();
   Y ob2 = new Y();
   MyEvent evt = new MyEvent();
   evt.SomeEvent += ob1.handler;
   evt.SomeEvent += ob2.handler;
   evt.OnSomeEvent();
   evt.OnSomeEvent();
 }

}

      </source>

Generic Anonymous Methods

<source lang="csharp"> public delegate void ADelegate<T>(T tvalue); public class MyClass{

   public void MethodA() {
       ADelegate<int> del=delegate(int var) {
       };
   }

} public class YClass<T>{

   public delegate void BDelegate(T tValue);
   public void MethodA() {
       BDelegate del=delegate(T tValue) {
       };
   }

}

</source>

Generic Delegate and non-generic delegate

<source lang="csharp"> using System; using System.Collections.Generic; using System.Text; public delegate void MyGenericDelegate<T>(T arg); public delegate void MyDelegate(object arg); class Program {

   static void Main(string[] args) {
       MyDelegate d = new MyDelegate(MyTarget);
       d("More string data");
       MyDelegate d2 = new MyDelegate(MyTarget);
       d2(9);
       MyGenericDelegate<string> strTarget =
           new MyGenericDelegate<string>(StringTarget);
       strTarget("Some string data");
       MyGenericDelegate<int> intTarget = IntTarget;
       intTarget(9);
       Console.ReadLine();
   }
   static void MyTarget(object arg) {
       if (arg is int) {
           int i = (int)arg;
           Console.WriteLine("++arg is: {0}", ++i);
       }
       if (arg is string) {
           string s = (string)arg;
           Console.WriteLine("arg in uppercase is: {0}", s.ToUpper());
       }
   }
   static void StringTarget(string arg) {
       Console.WriteLine("arg in uppercase is: {0}", arg.ToUpper());
   }
   static void IntTarget(int arg) {
       Console.WriteLine("++arg is: {0}", ++arg);
   }

}

</source>

Generics and Delegates

<source lang="csharp"> using System; public delegate void DelegateClass(int data); public class Starter {

   public static void Main() {
       DelegateClass del1 = MethodA<int>;
       del1(5);
       DelegateClass del2 = MethodA;
       del1(10); // inferred
   }
   public static void MethodA<T>(T data) {
       Console.WriteLine("MethodA ({0})", data);
   }

}

</source>