using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace DelegateEventDemo
{
    
    public delegate void AddEvent(object sender,EventArgs e);

    class DelegateHandler
    {
        
        public event AddEvent OnAdditionToList;
        
        public ArrayList al = new ArrayList();

        public DelegateHandler()
        {
           // Registering  the Changed method to event
            OnAdditionToList += new AddEvent(Changed);
        }

        public void OnListChanged(EventArgs e)
        {
            // Publish the event : Listening
            if (OnAdditionToList != null)
                OnAdditionToList(this, e);
        }

        private void Changed(object sender,EventArgs e)
        {
            // Notify the user
            Console.WriteLine("New element has been inserted into the list.");
        }


        public ArrayList Add(int num)
        {
            al.Add(num);
            // Fier the event it on occure 
            OnListChanged(EventArgs.Empty);
            return al;
        }

        public ArrayList Get()
        {
            return al;
        }

    }

    
    
    class Program
    {
        static void Main(string[] args)
        {
            DelegateHandler dh = new DelegateHandler();

            // Client side handling of event
            dh.OnAdditionToList += new AddEvent(ClientFunction);

            for (int i = 1; i <= 10; i++)
                dh.Add(i * 10);

            ArrayList al = dh.Get();

            for (int i = 0; i < al.Count; i++)
                Console.WriteLine(al[i].ToString());

            Console.ReadLine();
        }


        public static void ClientFunction(object sender, EventArgs e)
        {
            Console.WriteLine("Client handler is called.");


        }


    }
}