gistfile1.txt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    public class EventStateManager
    {

        IStateMachine currentState;

        public EventStateManager()
        {
            //set the initial state @todo accessor?
            currentState = MyChildSingletonA.Instance;

        }
        //in the state patten, this is used to execute the current state
        //not sure if this is relevant to this system???
        public void Update()
        {

            currentState.Execute(this);
        }

        public void ChangeState(IStateMachine newState)
        {
            //probably want to throw exception instead
            if ((currentState == null) || (newState == null))
                return;

            currentState.Exit(this);

            currentState = newState;

            currentState.Entry(this);


        }


        static void Main(string[] args)
        {

            EventStateManager esm = new EventStateManager();
            esm.ChangeState(MyChildSingletonB.Instance);
            esm.ChangeState(MyChildSingletonA.Instance);
            esm.ChangeState(MyChildSingletonB.Instance);



            Console.ReadKey();
        }
    }




    public class SingletonBase<T> where T : SingletonBase<T>, new()
    {

        private static T _instance = new T();
        public static T Instance
        {
            get
            {
                return _instance;
            }
        }



    }

    public interface IStateMachine
    {
        void Entry(EventStateManager esm);
        void Execute(EventStateManager esm);
        void Exit(EventStateManager esm);
    }

    public class MyChildSingletonA : SingletonBase<MyChildSingletonA>, IStateMachine
    {
        public void Entry(EventStateManager esm)
        {
            Console.WriteLine("entry in here");
        }
        public void Execute(EventStateManager esm)
        {
            Console.WriteLine("executing in here");
        }
        public void Exit(EventStateManager esm)
        {
            Console.WriteLine("exiting in here");
        }
    }

    public class MyChildSingletonB : SingletonBase<MyChildSingletonB>, IStateMachine
    {
        public void Entry(EventStateManager esm)
        {
            Console.WriteLine("entry - the other one");
        }
        public void Execute(EventStateManager esm)
        {
            Console.WriteLine("executing the other one");
        }
        public void Exit(EventStateManager esm)
        {
            Console.WriteLine("exiting the other one");
        }

    }




}