UI doesn't refresh with calculated fields in silverlight

Just a thought…  Could you have a read only property MyCalcField  that does the calculations on the fly and simply raise PropertyChanged event for it when underlying data changes?  For example, if a child in the list changes and you need to refresh that field in the root object, you can call this.Parent.Parent.RefreshCalculatedField where RefreshCalculatedField has OnPropertyChanged(“MyCalcField”)

Sergey Barskiy

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I've been working in a project with silverlight that has a BO with a calculated field derived from its own fields and another BO with a calculated field that comes from a BusinessList. In the latter BO, the Performance from its children is tallied to give the overall performance.

The problem comes in with silverlight. The UI doesn't refresh the controls bound to the calculated field whenever the fields that the calculated field depends on is changed. To solve the problem with the first BO, I created a managed CSLA property to hold the calculated value, and update it when the fields it depends on changed. It doesn't look natural, and if I'm not careful, bugs might creep in but it works.

For the second BO with a BusinessList, I also created another managed property to hold the value but in addition, I needed to override the CopyStateCompleted and added this code:

protected override void CopyStateCompleted()
{
   base.CopyStateCompleted;
   SuccessFactors.ChildChanged +=
       (sender, e) => SetProperty<decimal>(PerformanceProperty, SuccessFactors.Performance) ;
}

Again, it works well, the UI now updates, but it is not really intuitive.
Is there a better way to achieve the same effect?