Observer

//    Full Tutorial on indiedevart.wordpress.com

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

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            Enemy subject = new Enemy();

            IObserver observer1 = new UserInteface();
            subject.Subscribe(observer1);

            subject.Subscribe(new DifferentUnit());
            subject.Health++;
            Console.WriteLine("--------------------");
            subject.Unsubscribe(observer1);
            subject.Health--;
            Console.ReadLine();
        }
    }
    public class Enemy : IEnemy
    {
        private List<IObserver> observers = new List<IObserver>();
        private int _health=10;
        public int Health
        {
            get { return _health; }
            set
            {
                _health = value;
                Notify();
            }
        }

        public void Notify()
        {
            observers.ForEach(x => x.Update());
        }

        public void Subscribe(IObserver observer)
        {
            observers.Add(observer);
        }

        public void Unsubscribe(IObserver observer)
        {
            observers.Remove(observer);
        }
    }

    interface IEnemy
    {
        void Subscribe(IObserver observer);
        void Unsubscribe(IObserver observer);
        void Notify();
    }
    public class UserInteface : IObserver
    {

        public void Update()
        {
            Console.WriteLine("Interface Updated");
        }
    }
    public class DifferentUnit : IObserver
    {

        public void Update()
        {
            Console.WriteLine("Relation Updated");
        }
    }

    public interface IObserver
    {
        void Update();
    }
}