Exploring the C# Dynamic Type

Dynamic.cs

using System;
using System.Collections.Generic;
using System.Dynamic;

namespace DynamicTest
{
    class Program
    {
        static void Main(string[] args)
        {
            dynamic test = new MyDynamicObject();
            test.FirstName = "Boaz";

            Console.WriteLine(test.FirstName);
            // RuntimeException:
            //Console.WriteLine(test.LastName);

            dynamic exp = new ExpandoObject();
            exp.FirstName = "Boaz";

            Console.WriteLine(exp.FirstName);
            // RuntimeException:
            //Console.WriteLine(exp.LastName);

            Console.WriteLine(Add(1, 2));
            Console.WriteLine(Add("Bo", "az"));

            A a = new A() { FirstName = "Boaz object A" };
            B b = new B() { FirstName = "Boaz object B" };

            PrintDynamic(a);
            PrintDynamic(b);

            PrintObject(a);
            // NullreferenceExcption at runtime!
            //PrintObject(b);

            Console.ReadKey();
        }

        static dynamic Add(dynamic a, dynamic b)
        {
            return a + b;
        }

        static void PrintObject(object x)
        {
            A y = x as A;
            Console.WriteLine(y.FirstName);
        }

        static void PrintDynamic(dynamic x)
        {
            Console.WriteLine(x.FirstName);
        }

    }

    class A
    {
        public string FirstName { get; set; }
    }

    class B
    {
        public string FirstName { get; set; }
    }

    class MyDynamicObject : DynamicObject
    {

        Dictionary<string, object> _Values = new Dictionary<string, object>();

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            if (_Values.ContainsKey(binder.Name))
                result = _Values[binder.Name];
            else
                result = null;

            return true;
        }

        public override bool TrySetMember(SetMemberBinder binder, object value)
        {
            if (!_Values.ContainsKey(binder.Name))
                _Values.Add(binder.Name, value);
            else
                _Values[binder.Name] = value;

            return true;
        }

    }
}