Allow you to set properties on a command, before it is executed. This will let you set Query parameters, paging, and etc.

commands.cs

class Program
    {
        public static Dictionary<Type, object> Stubs = new Dictionary<Type, object>
        {
            {
                typeof (GetUserById), new StubGetUserById(x => new Person { Name = string.Format("{0} {1} {2}", x.FirstName, x.LastName, "Test") } )
            }
        };

        static void Main(string[] args)
        {
            var query =
            Command<GetUserById>(x =>
            {
                x.FirstName = "Khalid";
                x.LastName = "Abuhakmeh";
            }).Execute();

            Console.WriteLine(query.Name);
            Console.ReadLine();
        }

        private static TCommand Command<TCommand>(Action<TCommand> init = null)
            where TCommand : class
        {
            // pretend this is some fancy IoC Container
            var command = Stubs[typeof(TCommand)] as TCommand;

            if (init != null)
                init(command);

            return command;
        }

        public class GetUserById
        {
            public virtual Person Execute()
            {
                return new Person { Name = string.Format("{0} {1}", FirstName, LastName) };
            }

            public string LastName { get; set; }
            public string FirstName { get; set; }
        }

        public class StubGetUserById : GetUserById
        {
            private readonly Func<GetUserById, Person> _result;

            public StubGetUserById(Func<GetUserById, Person> result)
            {
                _result = result;
            }

            public override Person Execute()
            {
                return _result(this);
            }
        }

        public class Person
        {
            public string Name { get; set; }
        }
    }