using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public class A { }

    public class B : A { }

    public interface IInterface { }

    public class C : IInterface { }

    public class D : B, IInterface { }

    public class TypeSerializer

    {

        public TypeSerializer(Type type) { Type = type; }

        public Type Type { get; private set; }

        public override string ToString() { return "TypeSerializer for " + Type.Name; }

    }

​

    private static readonly IEnumerable<TypeSerializer> TypeSerializers = new List<TypeSerializer>

    {

        new TypeSerializer(typeof(A)),

        new TypeSerializer(typeof(B)),

        new TypeSerializer(typeof(IInterface))

    };

​

    public static void Main()

    {

        var objects = new object[]

        {

            new A(),

            new B(),  

            new C(),

            new D()

        };

        foreach (var obj in objects)

        {

            Console.WriteLine(obj.GetType().Name + " => " + FindBestTypeSerializer(obj));

        }

    }

​

    private static TypeSerializer FindBestTypeSerializer(object obj)

    {

        var runtimeType = obj.GetType();

        return TypeSerializers

            .Where(ts => ts.Type.IsAssignableFrom(runtimeType))

            .Aggregate((ts1, ts2) =>

            {

                if (ts1 == null)

                {

                    return ts2;

                }

                var t1 = ts1.Type;

                var t2 = ts2.Type;

                if (t1.IsAssignableFrom(t2))

                {

                    return ts2;

                }

                if (t2.IsAssignableFrom(t1))

                {

                    return ts1;

                }

                if (t1.IsInterface)

                {

                    if (t2.IsInterface)

                    {

                        throw new Exception("Conflicting type serializers - both are interfaces");

                    }

                    return ts2;

                }

                return ts1;

            });

    }

}