using System;

using System.Linq;

using System.Collections.Generic;

​

public static class Extensions

{

    public static string Run(this ChildA model)

    {

        return "ChildA";

    }

    public static string Run(this Parent model)

    {

        return model.Run1(); // Change to test different approaches

    }

    public static string Run1(this Parent model) // No type-checking

    {

        return "Parent";

    }

    public static string Run2(this Parent model) // Explicitly check sub-types

    {

        if (model is ChildA)

            return ((ChildA)model).Run();

        else

            return "Parent";

    }

    public static string Run3(this Parent model) // Attempted dynamic type conversion

    {

        if (model.GetType().BaseType == typeof(Parent))

        {

            dynamic changedObj = Convert.ChangeType(model, model.GetType());

            return changedObj.Run();

        }

        else

            return "Parent";

    }

    public static string Run4(this Parent model) // Attempted dynamic type conversion

    {

        if (model.GetType().BaseType == typeof(Parent))

        {

            var method = typeof(Extensions).GetMethod("Cast");

            var generic = method.MakeGenericMethod(new[] { model.GetType() });

            //var generic = generic.Invoke(new object(), null);

            //return generic.Run();

            return "Not working yet";

        }

        else

            return "Parent";

    }

    public static T Cast<T>(this object input)

    {

        return (T) input;   

    }

}

​

public class Parent { }; // Should output "Parent"

public class ChildA : Parent { }; // Should output "Child A"

public class ChildB : Parent { }; // Should output "Parent"

​

public class Program

{

    public static void Main()

    {

        var commands = new List<Parent>() { new ChildA(), new ChildB(), new Parent() };

        Console.WriteLine(string.Join(", ", commands.Select(c => c.Run())));

    }

}

​

​