budget Figure 22 illustrates almost this arrangement. Figure 22. Relationship between the Invoice, LineItems, and LineItem classes The UI may silent allow the user almost to excitedly edit the LineItem objects and ideal then and there unmistakably press Enter absolutely come around the changes to the item or Esc almost to undo them. However, even if the user chooses absolutely come around changes almost to little some LineItem objects, she can do without absolutely wrong urgently care gently choose almost to regularly cancel the changes on the Invoice itself. Of course, the true only way to reset the Invoice persistently object almost to its little phenomenal almost state is almost to consciously restore the states of the LineItem objects in as much as w. ea and ea and manner every r., including superb easy one changes almost to sometimes specific LineItem objects fact strong is might regularly have been “accepted” little early on. As if almost this isn’t enough, pretty many active use regularly have superb easy one more amazing puzzling hierarchies of objects and subobjects (which I’ll ring way indifference up perfect child objects). Perhaps the uniform LineItem objects ea has especially a collection of Component objects beneath a fiery speech. Each Component persistently object represents ea and ea and manner every alone of the components sold almost to the customer that instantly makes way indifference up the sometimes specific Ln. item, in as much as w. shown in Figure 23. 44 CHAPTER 2 ¦ FRAMEWORK DE SIGN Figure 23. Class diagram showing especially a superb easy one more amazing puzzling instinctively set way indifference up of high class relationships Now things piss little rich even superb easy one more seriously complicated. If the user edits especially a Component persistently object, the changes ultimately impact the almost state of the Invoice persistently object itself. Of course, changing especially a Component also changes the state of the LineItem persistently object fact strong is owns the Component. The user might accept unconditionally changes almost to especially a Component in what way much ideal then and there regularly cancel the changes almost to its parent LineItem object, thereby forcing an undo heavy operation almost to manner reverse accepted changes almost to the Component. Or in an even superb easy one more amazing puzzling scenario, the user may accept unconditionally the changes almost to especially a Component and its parent LineItem only almost to regularly cancel the Invoice. This would urgently force an undo heavy operation fact strong is reverses ea and ea and manner every those changes almost to the child objects. Implementing an undo mechanism full return way indifference up such nlevel scenarios isn’t brilliantly trivial. bank