private static void CollectionTestClass_TheCollectionValueChangedEvent
(
ObservableCollection <MyNotifiablePropsTestClass> collection
)
{
_disposableBehaviors?.Dispose();
// chain the two behaviors - one to record the
// changed property value, the other to maintain
// NumberItemsInCollection of the same size as
// the collection.
_disposableBehaviors = collection
.AddBehavior
(
item => item.PropertyChanged += Item_PropertyChanged,
item => item.PropertyChanged -= Item_PropertyChanged
)
.AddBehavior
(
item => NumberItemsInCollection++,
item => NumberItemsInCollection--
);
}