Question

I have a two dependency properties(both List of strings) in a custom user control.The binding for one of these dependency properties can be changed several times for the life of the application. I need to do some action in the user control when the binding is changed, and I need to access all the dependency properties in the class for doing the action.

For example,

public class UC:UserControl
{
 public List<string> AvailableItems
        {
            get { return (List<string>)this.GetValue(AvailableItemsProperty); }
            set { this.SetValue(AvailableItemsProperty, value);  }
        }
        public static readonly DependencyProperty AvailableItemsProperty = DependencyProperty.Register(
          "AvailableItems", typeof(List<string>), typeof(ItemSelectionUserControl), new FrameworkPropertyMetadata(OnAvailableItemsChanged) { BindsTwoWayByDefault = true });

        public List<string> SelectedItems
        {
            get { return (List<string>)this.GetValue(SelectedItemsProperty); }
            set { this.SetValue(SelectedItemsProperty, value); }
        }
            public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.Register(
              "SelectedItems", typeof(List<string>), typeof(ItemSelectionUserControl), new FrameworkPropertyMetadata { BindsTwoWayByDefault = true });   

 public static void OnAvailableItemsChanged(DependencyObject sender,  DependencyPropertyChangedEventArgs e)
        {
           //How to access SelectedItems here??
        } 

    }

The trouble is the the callback when dependency property changed should be static, so how can I access the non static dependency property wrapper in the function?? Or is there any other way to do this??

Answer 1

Use the following:

public static void OnAvailableItemsChanged(DependencyObject sender,  DependencyPropertyChangedEventArgs e)
{
   UC uc = sender as UC;
   List<string> selectedItems = uc.SelectedItems;
}