d the referenced structure be deleted?•If a (formerly shared) structure is not deleted from the heap when the last pointer referencing it is destroyed, you have a memory leak.•If a shared structure is deleted when there are other valid pointers still holding its address, these pointers become dangling references - problems will occur immediately on use of any of these pointers to attempt to access the deleted structure.Explain the "Observer Design Pattern". (2 marks) –Intent•Define a one-to many dependency among objects so that when one object changes state, all its dependents are notified and updated automatically.••Motivation–Common in interactive programs to have some “data structure” object with aspects displayed in several different views (selection of views defined by user);when data object changed, would like dependent views updated to reflect new state;as views vary, don’t want to hard-wire relations between data object and dependent viewsNot relatedEach “design pattern” systematically names, explains, and evaluates an important recurring design in object-oriented systems. Our goal is to capture design experience in a form that people can use effectively.Gamma et alHow are "use cases" employed in the development of the design of a program using classes. (1 mark) •“Use case” analysis focuses on how “actors” (ie humans for the most part) use your overall system to accomplish tasks.•What object picked up student request?•What object created to represent that request?•Where (to which object) was that object sent?•What happened there?How is "scenario analysis" used in the process of refining a design. (1 mark) •Run through scenarios of how program might work, listening to expert’s explanation Sketch an "object interaction diagram" that illustrates how, in your graphics display version of your...
