从一个实现INotifyPropertyChanged的基类继承

Question

I've been using the following bit of code in a cookie cutter fashion, across dozens of classes

public event PropertyChangedEventHandler PropertyChanged;

protected void NotifyPropertyChanged(string propertyName)
{
   if (PropertyChanged != null)
   {
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
   }
}

All of these classes implement INotifyPropertyChanged . To silence my DRY alarms, lately I've been refactoring these classes to inherit my base class PropertyNotifier whose only purpose is to provide NotifyPropertyChanged for classes that inherit from it -- which are the dozens of ViewModel classes in my huge project.

It feels lazy and a bit dirty. Am I hurting performance or breaking good design practices? I figure if change notification was supposed to be this easy, there would be a base class already in the WPF framework that does what my PropertyNotifier class does.

Note that, for a lot of reasons, I've been having performance issues with my UI responsiveness -- mostly due to a large number of controls. So I'm looking to trim the fat wherever I can. Any ideas?

Answer 1

This is a very common base class to have in WPF or Silverlight development and won't noticeably affect performance. The only problem I have with PropertyNotifier as a base class results from being restricted to single inheritance but that tends to be a rare issue with the type of class you'll need it for.

Answer 2

Yes, that's very common practice. For a large scale application it becomes necessary to have this kind of base class. We had also created a BaseViewModel for the same purpose; we also implemented a lot of common code(across ViewModels) in this base class like logging, displaying error messages, initializing WCF proxy objects etc.

Answer 3

Another implementation is the Model class of the WPF Application Framework (WAF) . It does exactly the same.