Question

I have a model class that has a Saved event. The idea is that if two viewmodels use that model object, if one of them changes it, the other will be updated.

Do I have to remove the event handler when I am no longer using its view model? Here is my code:

protected AbstractEntityViewModel(AbstractEntity ae)
{
    this.ae = ae;

    ae.Saved += delegate(object o, EventArgs e) 
    { 
        base.OnPropertyChanged(null);
    };
}

Is this ok, or do I need to change this so that I can -= get rid of the delegate when the viewmodel is no longer used?

Answer 1

Long and short of it is yes. The secondary object can not be disposed of if the AbstractEntity object still has a reference to it. IF there is a chance that the object will be disposed and the Event is still around (this holds true for static events too) then you need to manually remove the eventhandler or the object will not be disposed.