/// <inheritdoc />
/// <summary>
/// Remove the observer for a given notifyContext from an observer list for a given Notification name.
/// </summary>
/// <param name="notificationName">which observer list to remove from </param>
/// <param name="notifyContext">remove the observer with this object as its notifyContext</param>
public virtual void RemoveObserver(string notificationName, object notifyContext)
{
IList <IObserver> observers;
if (!ObserverMap.TryGetValue(notificationName, out observers))
{
return;
}
for (var i = 0; i < observers.Count; i++)
{
if (!observers[i].CompareNotifyContext(notifyContext))
{
continue;
}
observers.RemoveAt(i);
break;
}
// Also, when a Notification's Observer list length falls to
// zero, delete the notification key from the observer map
if (observers.Count == 0 && ObserverMap.ContainsKey(notificationName))
{
ObserverMap.Remove(notificationName);
}
}
/// <inheritdoc />
/// <summary>
/// Register an <c>IObserver</c> to be notified
/// of <c>INotifications</c> with a given name.
/// </summary>
/// <param name="notificationName">the name of the <c>INotifications</c> to notify this <c>IObserver</c> of</param>
/// <param name="observer">the <c>IObserver</c> to register</param>
public virtual void RegisterObserver(string notificationName, IObserver observer)
{
if (!ObserverMap.ContainsKey(notificationName))
{
ObserverMap.Add(notificationName, new List <IObserver>());
}
ObserverMap[notificationName].Add(observer);
}
/// <inheritdoc />
/// <summary>
/// Notify the <c>IObservers</c> for a particular <c>INotification</c>.
/// </summary>
/// <remarks>
/// <para>
/// All previously attached <c>IObservers</c> for this <c>INotification</c>'s
/// list are notified and are passed a reference to the <c>INotification</c> in
/// the order in which they were registered.
/// </para>
/// </remarks>
/// <param name="notification"></param>
public virtual void NotifyObservers(INotification notification)
{
// Get a reference to the observers list for this notification name
IList <IObserver> observersRef;
if (!ObserverMap.TryGetValue(notification.Name, out observersRef))
{
return;
}
// Copy observers from reference array to working array,
// since the reference array may change during the notification loop
var observers = new List <IObserver>(observersRef);
foreach (var observer in observers)
{
observer.NotifyObserver(notification);
}
}
