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Publish Subscribe C#



This is a class which holds the information about the event.  

    public class TimeEventArgs : EventArgs
    {
        public TimeEventArgs(string currentTime)
        {
            this.CurrentTime = currentTime;
        }

        public string CurrentTime;
    }

This is a Subject class (Publisher) that the other classes will observe. So it publishes a handler so that other observer classes can subscribe to it.

    public class Clock
    {
        public delegate void SecondChangeHandler(object clock, TimeEventArgs e);

        public SecondChangeHandler OnSecondChange;

        public void RunClock()
        {
            for (int i = 0; i <= 4; i++)
            {
                Thread.Sleep(1000);

                TimeEventArgs te = new      TimeEventArgs(DateTime.Now.ToString("HH:mm:ss"));

                if (OnSecondChange != null)
                {
                    OnSecondChange(this, te);
                }
            }
        }
    }

This is a Fisrt Observer class which is subscribed to Clock class

    public class DisplayClock
    {
        public void Subscribe(Clock clock)
        {
            clock.OnSecondChange += new Clock.SecondChangeHandler(TimeChanged);
        }

        private void TimeChanged(object clock, TimeEventArgs te)
        {
            Console.WriteLine("Time Changed :: " + te.CurrentTime);
        }
    }


This is a Second Observer class which is subscribed to Clock class

    public class LogClock
    {
        public void Subscribe(Clock clock)
        {
            clock.OnSecondChange += new    Clock.SecondChangeHandler(LogTimeChanged);
        }

        private void LogTimeChanged(object clock, TimeEventArgs te)
        {
            Console.WriteLine("Log Time : " + te.CurrentTime);
        }
    }


Now test the Publish Subscribe

        static void Main(string[] args)
        {
            Clock clock = new Clock();

            DisplayClock dc = new DisplayClock();
            dc.Subscribe(clock);

            LogClock lc = new LogClock();
            lc.Subscribe(clock);

            clock.RunClock();

            Console.ReadLine();
        }

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