/// <summary>
/// Subscribes a delegate to an event.
/// </summary>
/// <param name="action">The delegate that gets executed when the event is published.</param>
/// <param name="threadOption">Specifies on which thread to receive the delegate callback.</param>
/// <param name="keepSubscriberReferenceAlive">When <see langword="true"/>, the <see cref="PubSubEvent"/> keeps a reference to the subscriber so it does not get garbage collected.</param>
/// <returns>A <see cref="SubscriptionToken"/> that uniquely identifies the added subscription.</returns>
/// <remarks>
/// If <paramref name="keepSubscriberReferenceAlive"/> is set to <see langword="false" />, <see cref="PubSubEvent"/> will maintain a <see cref="WeakReference"/> to the Target of the supplied <paramref name="action"/> delegate.
/// If not using a WeakReference (<paramref name="keepSubscriberReferenceAlive"/> is <see langword="true" />), the user must explicitly call Unsubscribe for the event when disposing the subscriber in order to avoid memory leaks or unexpected behavior.
/// <para/>
/// The PubSubEvent collection is thread-safe.
/// </remarks>
public virtual SubscriptionToken Subscribe(Action action, ThreadOption threadOption, bool keepSubscriberReferenceAlive)
{
IDelegateReference actionReference = new DelegateReference(action, keepSubscriberReferenceAlive);
EventSubscription subscription;
switch (threadOption)
{
case ThreadOption.PublisherThread:
subscription = new EventSubscription(actionReference);
break;
case ThreadOption.BackgroundThread:
subscription = new BackgroundEventSubscription(actionReference);
break;
case ThreadOption.UIThread:
if (SynchronizationContext == null)
{
throw new InvalidOperationException("EventAggregatorNotConstructedOnUIThread");
}
subscription = new DispatcherEventSubscription(actionReference, SynchronizationContext);
break;
default:
subscription = new EventSubscription(actionReference);
break;
}
return(InternalSubscribe(subscription));
}
/// <summary>
/// Subscribes a delegate to an event.
/// </summary>
/// <param name="action">The delegate that gets executed when the event is published.</param>
/// <param name="threadOption">Specifies on which thread to receive the delegate callback.</param>
/// <param name="keepSubscriberReferenceAlive">When <see langword="true"/>, the <see cref="CompositePresentationEvent{TPayload}"/> keeps a reference to the subscriber so it does not get garbage collected.</param>
/// <param name="filter">Filter to evaluate if the subscriber should receive the event.</param>
/// <returns>A <see cref="SubscriptionToken"/> that uniquely identifies the added subscription.</returns>
/// <remarks>
/// If <paramref name="keepSubscriberReferenceAlive"/> is set to <see langword="false" />, <see cref="CompositePresentationEvent{TPayload}"/> will maintain a <see cref="WeakReference"/> to the Target of the supplied <paramref name="action"/> delegate.
/// If not using a WeakReference (<paramref name="keepSubscriberReferenceAlive"/> is <see langword="true" />), the user must explicitly call Unsubscribe for the event when disposing the subscriber in order to avoid memory leaks or unexepcted behavior.
///
/// The CompositePresentationEvent collection is thread-safe.
/// </remarks>
public virtual SubscriptionToken Subscribe(Action <TPayload> action, ThreadOption threadOption, bool keepSubscriberReferenceAlive, Predicate <TPayload> filter)
{
IDelegateReference actionReference = new DelegateReference(action, keepSubscriberReferenceAlive);
IDelegateReference filterReference;
if (filter != null)
{
filterReference = new DelegateReference(filter, keepSubscriberReferenceAlive);
}
else
{
filterReference = new DelegateReference(new Predicate <TPayload>(delegate { return(true); }), true);
}
EventSubscription <TPayload> subscription;
switch (threadOption)
{
case ThreadOption.PublisherThread:
subscription = new EventSubscription <TPayload>(actionReference, filterReference);
break;
case ThreadOption.BackgroundThread:
subscription = new BackgroundEventSubscription <TPayload>(actionReference, filterReference);
break;
case ThreadOption.UIThread:
subscription = new DispatcherEventSubscription <TPayload>(actionReference, filterReference, null);
break;
default:
subscription = new EventSubscription <TPayload>(actionReference, filterReference);
break;
}
return(base.InternalSubscribe(subscription));
}