publisher

gistfile1.cs

public class LocationPublisher : IObservable<Location>
    {
        private List<IObserver<Location>> observers;

        public LocationPublisher()
        {
            observers = new List<IObserver<Location>>();
        }

        public IDisposable Subscribe(IObserver<Location> observer)
        {
            if (!observers.Contains(observer))
                observers.Add(observer);

            return new Unsubscriber(observers, observer);
        }

        public void TrackLocation(Nullable<Location> loc)
        {
            foreach (var observer in observers)
            {
                if (!loc.HasValue)
                    observer.OnError(new LocationUnknownException());
                else
                    observer.OnNext(loc.Value);
            }
        }

        public void EndTransmission()
        {
            foreach (var observer in observers.ToArray())
                observer.OnCompleted();

            observers.Clear();
        }
    }