// *** Constructors ***
public VirtualizingDataList(IDataListSource <T> dataListSource)
{
// Validate the parameters
if (dataListSource == null)
{
throw new ArgumentNullException("dataListSource");
}
// Set the fields and subscribe for collection updates
this.dataListSource = dataListSource;
dataListSource.Subscribe(this);
}
public IDisposable Subscribe(IUpdatableCollection collection)
{
// Store the IUpdatableCollection in a WeakReferenceList
WeakReference <IUpdatableCollection> collectionReference = updateSubscriptions.AddAndReturnReference(collection);
// Subscribe to the source if there is not currently a subscription in place
if (sourceUpdateDisposable == null)
{
sourceUpdateDisposable = source.Subscribe(this);
}
// Return an IDisposable to remove the subscription
return(new DelegateDisposable(delegate()
{
updateSubscriptions.Remove(collectionReference);
UnsubscribeFromSourceIfNoSubscribers();
}));
}
