How to set bindings on CLR Properties using DataResource

It can be pretty annoying that bindings are only allowed on dependency properties of elements that are part of an element tree. For example, in all of these scenarios binding isn't allowed:

• on an InputBinding's CommandParameter (not a dependency property)
• on an object in an element's Resources if that object doesn't derive from Freezable (not part of an element tree)
• on an element set to a FrameworkElement’s Tag property (not part of an element tree)
• on a ValidationRule (not a dependency object)

This post introduces a new technique allowing you to add bindings to CLR properties and is a perfectly good workaround for all the scenarios above. it's good because it:

• helps you use binding in many more scenarios :)
• is very easy to use: just drop one source file (DataResource.cs) into your app and use it like this:

  
  <Window.Resources>
      
      <my:DataResource x:Key="actualWidth" BindingTarget="{Binding ActualWidth}"/>
  </Window.Resources>
  
  <my:MyControl>
      <my:MyControl.MyClrProperty>
          <my:DataResourceBinding DataResource="{StaticResource actualWidth}"/>
      </my:MyControl.MyClrProperty>
  </my:MyControl>
  

It works by using:

• Mike Hillberg's technique of using Freezable to gain access to the DataContext of the host element
• a custom markup extension to retrieve the object that the DataResource is bound to and returns this as the host of the markup extension

DataResource.cs
Download sample app with source code