Polymorphism Through Extension Methods?

Question

I have a class library which contain some base classes and others that are derived from them. In this class library, I\'m taking advantage of polymorphism to do what I want it t

Answer 1

Below is the minimal example showing how to mimic polymorphism with extension methods.

void Main()
{
    var elements = new Base[]{
        new Base(){  Name = "Base instance"},
        new D1(){    Name = "D1 instance"},
        new D2(){    Name = "D2 instance"},
        new D3(){    Name = "D3 instance"}

    };

    foreach(Base x in elements){
        x.Process();
    }
}

public class Base{
    public string Name;
}
public class D1 : Base {}
public class D2 : Base {}
public class D3 : Base {}


public static class Exts{

    public static void Process(this Base obj){
        if(obj.GetType() == typeof(Base)) Process(obj); //prevent infinite recursion for Base instances
        else Process((dynamic) obj);
    }

    private static void Process(this T obj) where T: Base
    {
        Console.WriteLine("Base/Default: {0}", obj.Name);
    }

    public static void Process(this D1 obj){
        Console.WriteLine("D1: {0}", obj.Name);
    }

    public static void Process(this D2 obj){
        Console.WriteLine("D2: {0}", obj.Name);
    }
}

Outputs:

    Base/Default: Base instance
    D1: D1 instance
    D2: D2 instance
    Base/Default: D3 instance