Question

How can I implement Delay property from .Net 4.5 (described here) on binding in .Net 4.0?

I know I cannot inherit from BindingBase as ProvideValue is sealed.

I could implement MarkupExtension but it means I now have to rewrite all properties from BindingExtension is there any other way?

Answer 1

I would create an AttachedProperty that specifies the amount of time to Delay. The AttachedProperty would start (or reset) a timer when the bound value changes, and would manually update the bound source when the specified amount of time gets reached.

You can use the following to update the source binding:

BindingOperations.GetBindingExpressionBase(
    dependencyObject, dependencyProperty).UpdateSource();

Edit

I was fixing a bug in some old code today and noticed it implemented a delayed property change notification using an Attached Behavior. I thought of this question, so followed the link that I had commented in the code, and found myself at a question I had posted a while ago on SO about delaying a binding. The top answer is the one I have implemented currently, which is some attached properties that updates the source of a binding after X milliseconds have passed.