// contravariance will delegates
public static void Main(string[] args)
{
ContravarianceDel del = DoSomething;
del(null);
Console.ReadKey();
}
static void Main(string[] args)
{
StreamWriter tw = new StreamWriter("dummy");
//Because both StreamWriter and StringWriter inherit from TextWriter
//This becomes a valid result
ContravarianceDel del = DoSomething;
del(tw);
Console.ReadKey();
}
static void Main(string[] args)
{
MaineCoon mc = new MaineCoon("Чейз");
Cat cat = mc;
ContravarianceDel del = CatInfo;
del((MaineCoon)cat); // Как по мне, так полная хрень!
mc.GetInfo();
Console.ReadKey();
}
public void DoTest()
{
// both return class inherits from TextWriter
// 共変性(covariance)
del = MethodStream;
del = MethodString;
// parameter StreamWriter also inherits TextWriter
// 反返性(contravariance)
contraDel = DoSomething;
Func <int, int, int> calc = (x, y) => x + y;
Console.WriteLine($"Func<int, int, int> calc = {calc(1, 2)}");
}
static void Main(string[] args)
{
Console.WriteLine("=========Contra-Covariance:Action============");
Action <object> actObject = SetObject;
// Um objeto que é instanciado com um argumento de tipo menos derivado
// é atribuído a um objeto instanciado com um argumento de tipo mais derivado.
// A compatibilidade da atribuição é revertida.
Action <string> actString = actObject;
Console.WriteLine("actObject=" + actObject.GetType()); // actObject = System.Action`1[System.Object]
Console.WriteLine("actString=" + actString.GetType()); // actString = System.Action`1[System.Object]
ContravarianceDel del = DoSomething;
Console.ReadKey();
}
static void Main(string[] args)
{
ContravarianceDel del = DoSomething;
}
public static void ContravarianceWithDelegates()
{
ContravarianceDel del = DoSomething;
}
public static void ContravarianceDemo()
{
ContravarianceDel del = DoSomething;
//possible because ContravarianceDel takes a StreamWriter, and TextWriter inherits from StreamWriter
}
public void useContravariance()
{
ContravarianceDel del2 = DoSomething;
}
public void teste()
{
ContravarianceDel del = DoSomething;
ContravarianceDel2 del2 = DoSomething;
}
public static void Run()
{
ContravarianceDel del = DoSomething;
}
public void Main()
{
ContravarianceDel del = this.DoSomething;
}
static void Main(string[] args)
{
//Because DoSomething can work with a text writer it can also work with a stream writer.
//This is contravariance.
ContravarianceDel del = DoSomething;
}
public void Ex4_Contravariance()
{
ContravarianceDel del = MethodContra;
del(new Derived()); // requires delegate type
}
public static void Test_Contravariance()
{
del = DoSomething;
del(null);
Console.ReadLine();
}
