using System;

using System.Collections;

​

public class Program

{

    public static void Main()

    {

            // instantiate listeners

            Police police = new Police();

            Fire fire = new Fire();

            Ambulance ambulance = new Ambulance();

​

            // instantiate broadcaster

            Call911 c911 = new Call911();

​

            // attach broadcaster (call911) to listners (police, ambulance, fire)

            c911.CallForHelp += police.OnCallTo911;

            c911.CallForHelp += fire.OnCallTo911;

            c911.CallForHelp += ambulance.OnCallTo911;

​

            //call to 911

            c911.createNotification("250 Humber Blvd.  - John Hinz - HELP - Crazy Students!!!!! ");

​

            Console.ReadLine();

​

    }

}

​

   public class Police

    {

        // police listner - signature must match event and delegate

        public void OnCallTo911(object sender, EmergencyInfo e)

        {

            Console.WriteLine("There is a Police call from " + e.address);

        }

​

    }

    public class Fire

    {

        // Fire listner - signature must match event and delegate

        public void OnCallTo911(object sender, EmergencyInfo e)

        {

            Console.WriteLine("There is a Fire call from " + e.address);

        }

​

    }

    public class Ambulance

    {

        // Ambulance listner - signature must match event and delegate

        public void OnCallTo911(object sender, EmergencyInfo e)

        {

            Console.WriteLine("There is a Ambulance call from " + e.address);

        }

​

    }

​

    public class Call911

    {

        // Call911's event

        public event EmergencyEvent CallForHelp;

​

​

        // a call to this method will notify listeners of the event

        public void createNotification(string msg)

        {

            // check to see if anyone is listening

            if (CallForHelp != null)

            {

                CallForHelp(this, new EmergencyInfo(msg));

            }

        }

    }

​

    // delegate for the event's signature

    public delegate void EmergencyEvent(object sender, EmergencyInfo e);

​

    // event information (holds address passed to listeners)

    public class EmergencyInfo : EventArgs

    {

        public string address { get; set; }

        public EmergencyInfo(string Address)

        {

            address = Address;

        }

    }

​