Duck Typing in C#

Let's be clear about it: there's nothing wrong about Duck Typing, as long as we used it on exceptional cases, and on a controlled environment like the duck typing project.

Here's a sample:

public interface ICanAdd
{
    int Add(int x, int y);
}

// Note that MyAdder does NOT implement ICanAdd, 
// but it does define an Add method like the one in ICanAdd:
public class MyAdder
{
    public int Add(int x, int y)
    {
        return x + y;
    }
}

public class Program
{
    void Main()
    {
        MyAdder myAdder = new MyAdder();

        // Even though ICanAdd is not implemented by MyAdder, 
        // we can duck cast it because it implements all the members:
        ICanAdd adder = DuckTyping.Cast<ICanAdd>(myAdder);

        // Now we can call adder as you would any ICanAdd object.
        // Transparently, this call is being forwarded to myAdder.
        int sum = adder.Add(2, 2);
    }
} 
  

Why restrict Duck Typing usage? Because (whenever possible) early interface identification lowers the typing mismatch. In my view, we should privilege early interface definition whenever possible.