Tip

The CLR wrapper for a DependencyProperty should do its job and nothing more

Explanation

The CLR wrapper for a Silverlight/WPF DependencyProperty exists purely as a convenience to the developer. The "real" value of a DependencyProperty is stored by the system and accessed by the GetValue and SetValue methods. In fact, parts of the system will only access the value in that manner (possible examples: XAML parser, storyboard animations, etc.). And even if that weren't the case, the fact that the DependencyProperty field is public means that other parts of an application might do so as well (and there is no way of knowing when or stopping them). Therefore, it's not possible to ensure that any custom logic added to the CLR property's set or get wrapper implementation will run every time the DependencyProperty is accessed. Unless you're a fan of inconsistent state, hard to find bugs, or the like, it is typically unwise to violate this convention.

Good Example

public int MyProperty
{
    get { return (int)GetValue(MyPropertyProperty); }
    set { SetValue(MyPropertyProperty, value); }
}

More information