Is it possible to return a read-only ObservableCollection that the caller can't modify?

问题

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.

回答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;
}

回答2:

Why do you need a read only ObservableCollection. If this collection is read only you don't need to observe it. Consider a Collection<T>

回答3:

Return a ReadOnlyObservableCollection instead:

private ReadOnlyObservableCollection<Message> _Messages;

public ReadOnlyObservableCollection<Message> Messages {
   get { this._Messages = this._Messages ?? new ReadOnlyObservableCollection(new ObservableCollection<Message>()); return this._Messages; }
}

回答4:

What about to use the ReadOnlyObservableCollection< T >

来源：https://stackoverflow.com/questions/6346948/is-it-possible-to-return-a-read-only-observablecollection-that-the-caller-cant

标签

c#-4.0

observablecollection

readonly