public abstract class BaseEntity : Entity

{

     protected BaseEntity()

     {

          base.EntityAspect.PropertyChanged += EntityAspectPropertyChanged; // This is probably NOT the right place to do this, but until we can find something better, this seems to work.  Suggestions?

     }



     private void EntityAspectPropertyChanged(object sender, PropertyChangedEventArgs e)

     {

          this.EntityAspectPropertyChangedInternal(sender, e);

     }

     

     protected virtual void EntityAspectPropertyChangedInternal(object sender, PropertyChangedEventArgs e)

     {

          if (e.PropertyName == "IsChanged") //take the Entity.EntityAspect.IsChanged property change

          {

               RaisePropertyChanged("IsChanged"); //and turn it into an Entity.IsChanged property change

          }

     }

}

public abstract class BaseChildEntity : BaseEntity

{

     protected abstract BaseEntity Parent { get; set; } 



     protected override void EntityAspectPropertyChangedInternal(object sender, System.ComponentModel.PropertyChangedEventArgs e)

     {     

          base.EntityPropertyChangedInternal(sender, e);

          if (e.PropertyName == "IsChanged" && this.EntityAspect.IsChanged)

          {

               //entity just got dirtied, so dirty the parent too

               this.Parent.EntityAspect.SetModified();

          }

     }

}

public partial class OrderDetail

{

     protected override BaseEntity Parent

     {

          get

          {

               return Order; //Expose the RelatedEntity>Order as this OrderDetail's Parent

          }

          set

          {

               Order = value as Order;

          }

     }

}

public partial class Order

{

     public double OrderTotal()

     {

          return Sum(this.OrderDetails);

     }



     private void OrderDetailPropertyChanged(object sender, PropertyChangedEventArgs e) //there is a horrible amount of code in this class that handles ensuring that this event handler is tied to each OrderDetail.PropertyChanged event.

     {

          this.RaisePropertyChanged("OrderTotal");

     }

     

}