Question

Consider the following code:

public ObservableCollection<Message> Messages {
   get { return new ObservableCollection<Message>(); }
}

Is there anything I can do to prevent the caller code from adding/removing/changing items?

EDIT: Sorry, everyone, I just noticed it’s a dupe, but the accepted answer is wrong.

Answer 1

What about using ReadOnlyObservableCollection

Code would be:

public ReadOnlyObservableCollection<Message> Messages 
{
  get { return new ReadOnlyObservableCollection<Message>(new ObservableCollection<Message>()); }
}

Having read aboutReadOnlyObservableCollection Anti Pattern I realise the above is the not a good approach and may lead to subtle bugs. The suggested approach is:

public class MyClass
{
  public MyClass()
  {
    myCollection = new ObservableCollection<Message>();
    myReadOnlyCollection = new ReadOnlyObservableCollection<Message>(myCollection);
  }

  public ReadOnlyObservableCollection<Message> Messages 
  {
    get { return myReadOnlycollection; }
  }

  private readonly ObservableCollection<Message> myCollection;
  private readonly ReadOnlyObservableCollection<Message> myReadOnlyCollection;
}