//Contrvariance in Arugments
public static void Example()
{
DelegateA delegateA = HandleDemoEvent; // No variavnce
DelegateB delegateB = HandleDemoEvent; // Contravariance
DelegateC delegateC = HandleDemoEvent; // Contravariance
//ExampleVarianceDelegate.DelegateB delegateB1 = HandleDemoEventC; // Exception
//ExampleVarianceDelegate.DelegateC delegateC1 = HandleDemoEventB; // Exception
//ExampleVarianceDelegate.DelegateC delegateA1 = HandleDemoEventB; // Covariance doesn't work Exception
delegateA("", new EventArgs());
//delegateB("", new EventArgs()); //Exception, you can't call it with EventArgs
//delegateC("", new EventArgs()); //Exception, you can't call it with EventArgs
delegateB("", new KeyPressEventArgs('b'));
delegateC("", new MausePressEventArgs(new Object(), 1, 1, 1, 1));
// EVENTS The same rule
riseA += HandleDemoEvent;
riseB += HandleDemoEvent; //Contravariance
riseC += HandleDemoEvent; //Contravariance
//riceC += HandleDemoEventB; //Exceptoion
//riceB += HandleDemoEvent; // Covariance Exception
riseA.Invoke("", new EventArgs());
riseB.Invoke("", new KeyPressEventArgs('b'));
riseC.Invoke("", new MausePressEventArgs(new Object(), 1, 1, 1, 1));
}
static void Main(string[] args)
{
DelegateA delA = MethodA;
DelegateB delB = MethodA; // Contravariance
//DelegateA delA = new DelegateA( MethodA );
//DelegateB delB = new DelegateB( MethodA ); // Contravariance
}
static void Main(string[] args)
{
del += new DelegateB(India);
del += new DelegateB(USA);
del += new DelegateB(UK);
del.Invoke();
Console.ReadLine();
}
public static void Sample1()
{
DelegateA delegateA = new DelegateA(Square);
DelegateB delegateB = Increment;
var resultA = delegateA(3);
var resultB = delegateB(3);
Console.WriteLine(" Square: {0}", resultA);
Console.WriteLine("Increment: {0}", resultB);
Console.ReadLine();
}
static bool TestCompare(DelegateA a, DelegateB b)
{
return(a != b);
}
static bool TestCompare (DelegateA a, DelegateB b)
{
return a != b;
}
