using System;

using System.Collections;

using System.Collections.Generic;

​

namespace ConsoleApplication27

{

    class Program

    {

        static void Main(string[] args)

        {

            Customer cust = new Customer();

            OrderAddListener OAL = new OrderAddListener();

            cust.orderEvent+=OAL.EventListener;

            cust.AddOrder(new Order() { Desc = "Shoes", Price = 120, Quantity = 1 });

            cust.AddOrder(new Order() { Desc = "Jacket", Price = 40, Quantity = 30 });

            cust.AddOrder(new Order() { Desc = "Tv", Price = 600, Quantity = 1 });

            foreach (var o in cust)

​

            {

                Console.WriteLine(o.Desc+" " +o.Quantity+" "+ o.Price);

            }

        }

    }

​

    class OrderAddListener

    {

        public void EventListener(object sender,orderEventsArgs e)

        {

            Console.WriteLine("An order was added.  Here are the order details: Desc ={0} , Quantity = {1}, Price ={2}",e.order.Desc,e.order.Quantity,e.order.Price);

        }

    }

    public delegate void OrderDel(Object o, orderEventsArgs e);

    class Customer : IEnumerable<Order>

    {

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public event OrderDel orderEvent;

​

        private List<Order> _Orders { get; set; }

​

        public Customer()

        {

            _Orders = new List<Order>();

        }

​

        public void AddOrder(Order item)

        {

            _Orders.Add(item);

            if (orderEvent != null)

            {

                orderEvent(this, new orderEventsArgs(item));

            }

        }

​

        public IEnumerator<Order> GetEnumerator()

        {

            foreach (var item in _Orders)

            {

                yield return item;

            }

        }

​

        IEnumerator IEnumerable.GetEnumerator()

        {

            throw new NotImplementedException();

        }

    }

​

​

​

​

    public class orderEventsArgs:EventArgs

    {

       public Order order;

        public orderEventsArgs(Order o)

        {

            this.order = o;

        }

    }

​

    public class Order

    {

        public string Desc { get; set; }

        public decimal Price { get; set; }

        public int Quantity { get; set; }

    }

​

}

​