Why is ReadOnlyObservableCollection.CollectionChanged not public?

Question

Why is ReadOnlyObservableCollection.CollectionChanged protected and not public (as the corresponding ObservableCollection.CollectionChanged is)?

What is the use of a collection implementing INotifyCollectionChanged if I can't access the CollectionChanged event?

Answer 1

Here's the solution: CollectionChanged events on ReadOnlyObservableCollection

You have to cast the collection to INotifyCollectionChanged.

Answer 2

I've found a way for you of how to do this:

ObservableCollection<string> obsCollection = new ObservableCollection<string>();
INotifyCollectionChanged collection = new ReadOnlyObservableCollection<string>(obsCollection);
collection.CollectionChanged += new NotifyCollectionChangedEventHandler(collection_CollectionChanged);

You just need to refer to your collection explicitly by INotifyCollectionChanged interface.

Answer 3

I know this post is old, however, people should take their time to understand the patterns used in .NET before commenting. A read only collection is a wrapper on an existing collection that prevents consumers from modifying it directly, look at ReadOnlyCollection and you will see that it is a wrapper on a IList<T> which may or may not be mutable. Immutable collections are a different matter and are covered by the new immutable collections library

In other words, read only is not the same as immutable!!!!

That aside, ReadOnlyObservableCollection should implicitly implement INotifyCollectionChanged.