Csharp/CSharp Tutorial/delegate/Generic delegate

Create generic delegate from reflection

<source lang="csharp">using System; using System.Reflection; using System.Collections.Generic; delegate void ComputeDelegate<T>( T instance, Decimal percent ); public class Employee {

   public Decimal Salary;
   public Employee( Decimal salary ) {
       this.Salary = salary;
   }
   public void ComputeSalary( Decimal percent ) {
       Salary *= (1 + percent);
   }

} public class MainClass {

   static void Main() {
       List<Employee> employees = new List<Employee>();
       employees.Add( new Employee(40) );
       employees.Add( new Employee(65) );
       employees.Add( new Employee(95) );
       MethodInfo mi = typeof(Employee).GetMethod( "ComputeSalary", BindingFlags.Public | BindingFlags.Instance );
       ComputeDelegate<Employee> applyRaise = (ComputeDelegate<Employee> )Delegate.CreateDelegate(typeof(ComputeDelegate<Employee>), mi );
       foreach( Employee e in employees ) {
           applyRaise( e, (Decimal) 0.10 );
           Console.WriteLine( e.Salary );
       }
   }

}</source>

44.0
71.5
104.5

delegate constaints

<source lang="csharp">using System; public delegate R Operation<T1, T2, R>( T1 val1, T2 val2 )

   where T1: struct
   where T2: struct
   where R:  struct;

public class MainClass {

   public static double Add( int val1, float val2 ) {
       return val1 + val2;
   }
   static void Main() {
       Operation<int, float, double> op = new Operation<int, float, double>( Add );
       Console.WriteLine( "{0} + {1} = {2}", 1, 3.2, op(1, 3.2f) );
   }

}</source>

1 + 3.2 = 4.20000004768372

Generic Delegate

<source lang="csharp">using System; using System.Collections.Generic; delegate void FunctionToCall<T>(T value); class MainClass {

  static public void PrintString(string s)            
  {
     Console.WriteLine(s);
  }
  static public void PrintUpperString(string s)       
  {
     Console.WriteLine("{0}", s.ToUpper());
  }
  static void Main()
  {
     FunctionToCall<string> functionDelegate = PrintString;  
     functionDelegate += PrintUpperString;               
     functionDelegate("Hi There.");                              
  }

}</source>

Hi There.
HI THERE.

Generic Delegate list

<source lang="csharp">using System; using System.Collections.Generic; public delegate void MyDelegate<T>( T i ); public class DelegateList<T> {

   public void Add( MyDelegate<T> del ) {
       imp.Add( del );
   }
   public void CallDelegates( T k ) {
       foreach( MyDelegate<T> del in imp ) {
           del( k );
       }
   }
   private List<MyDelegate<T> > imp = new List<MyDelegate<T> >();

} public class MainClass {

   static void Main() {
       DelegateList<int> delegates = new DelegateList<int>();
       delegates.Add( PrintInt );
       delegates.CallDelegates( 42 );
   }
   static void PrintInt( int i ) {
       Console.WriteLine( i );
   }

}</source>

42

Return Type Inference With Multiple Returns

<source lang="csharp">using System; using System.ruponentModel;

   delegate T MyFunc<T>();
   class MainClass
   {
       static void WriteResult<T>(MyFunc<T> function)
       {
           Console.WriteLine(function());
       }
       static void Main()
       {
           WriteResult(delegate
           {
               if (1 > 2)
               {
                   return 10;
               }
               else
               {
                   return new object();
               }
           });
       }
   }</source>