Pattern for implementing INotifyPropertyChanged?

Question

I have seen the following pattern used for implementing INotifyPropertyChanged

private void NotifyPropertyChanged(string propertyName)
{
    PropertyChangedEvent         


        

Answer 1

It's the thread safe method of raising events. By assigning the publicly accessible PropertyChanged event locally before using it you ensure that it won't be different between the 'if' statement and the line actually raising the event.