using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        HandlerRegistry.Register<Message1, Message1Handler>();

        HandlerRegistry.Register<Message2, Message2Handler>();

        var messages = new List<MessageBase>()

        {

            new Message1(),

            new Message2()

        };

        foreach (var message in messages)

        {

            var handler = HandlerRegistry.Resolve(message);

            handler.Execute(message);               

        }       

    }

}

​

// abstract class MessageBase

public abstract class MessageBase

{

    public virtual void Action() // ...for examples sake

    {

        Console.WriteLine(GetType().Name);

    }

}

​

// interface IMessageHandler

public interface IMessageHandler

{

    void Execute<T>(T message) where T : MessageBase;

}

​

// static class HandlerRegistry (handler resolver)

public static class HandlerRegistry

{

    private static readonly Dictionary<string, Type> Handlers = 

        new Dictionary<string, Type>();

​

    public static void Register<T, T2>() where T2 : IMessageHandler

    {

        Handlers.Add(typeof(T).FullName, typeof(T2));

    }

​

    public static IMessageHandler Resolve<T>(T parameters)

    {

        var type = Handlers[parameters.GetType().FullName];

        return (IMessageHandler)Activator.CreateInstance(type);

    }

}

​

// impl

public class Message1 : MessageBase

{}

​

public class Message2 : MessageBase

{

    public override void Action()

    {

        Console.Write(@"Overriding ");

        base.Action();

    }

}

​

public class Message1Handler : IMessageHandler

{

    public void Execute<T>(T message) where T : MessageBase

    {

        Console.Write(@"MessageHandler1 > ");

        message.Action();

    }

}

​

public class Message2Handler : IMessageHandler

{

    public void Execute<T>(T message) where T : MessageBase

    {

        Console.Write(@"MessageHandler2 > ");

        message.Action();

        Console.WriteLine(@"...and then some");

    }

}