using System;

​

// Declaration of a contravariant generic interface

public interface IMyInt<in T>  // To try without contravariance, change to only <T>

{

    void SetItem(T item);

}

​

public class Program

{

    public static void Main()

    {

        // Normal part (without contravariance)

        MyClBase myClBase1 = new MyClBase();

        IMyInt<Base> obj1 = myClBase1;  // Direct assignment

​

        obj1.SetItem(new Derived());  // Call with an object of type Base

​

        // Part that uses contravariance

        MyClBase myClBase2 = new MyClBase();

        IMyInt<Derived> obj2 = myClBase2;  // Contravariance: Base interface assigned to Derived

​

        obj2.SetItem(new Derived());  // Call with an object of type Derived

    }

}

​

public class MyClBase : IMyInt<Base>

{

    public void SetItem(Base item)

    {

        item.Show();

    }

}

​

public class Base

{

    public virtual void Show()

    {

        Console.WriteLine("Base class method");

    }

}

​

public class Derived : Base

{

    public override void Show()

    {

        Console.WriteLine("Derived class method");

    }

}