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Generation Gap By Kurt Rehwinkel

Generation Gap By Kurt Rehwinkel. Generation Gap. Introduction – What is the Generation Gap? The author describes it as a pattern. It is potentially as much a strategy as much as a pattern. Generation Gap: Intent.

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Generation Gap By Kurt Rehwinkel

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  1. Generation GapByKurt Rehwinkel

  2. Generation Gap • Introduction – What is the Generation Gap? • The author describes it as a pattern. • It is potentially as much a strategy as much as a pattern

  3. Generation Gap: Intent • Support for auto-generation and regeneration of source code by software development tools. • To modify or extend generated code such that the regeneration of the source does not effect the implementation.

  4. Generation Gap: Applicability • Code is generated automatically. • Generated code is encapsulated. • Regenerated code retains form in interface and instance variables. • Generated classes do not tend to be integrated into inheritance hierarchies. To do so requires the ability to specify super-classes and may require multiple inheritance support in the language.

  5. Generation Gap: Participants • CoreClass • Abstract class containing tool generated implementation. • Never modified by hand. • Written and/overwritten by the software development tool. • ExtensionClass • A trivial subclass of CoreClass. • Provides concrete implementations and extends or overrides the behavior in the CoreClass. • Preserves developer generated software implementations. • Client • Instantiates and refers ONLY to ExtensionClass.

  6. Generation Gap: Structure

  7. Generation Gap: Example class Clock : public Clock_core { public: Clock(const char*); void Run(); virtual void SetTime(); virtual void SetAlarm(); virtual void Snooze(); virtual void Update(); private: void GetSystemTime(int& h, int& m, int& s); void SetSystemTime(int h, int m, int s); void Alarm(); private: float _time; float _alarm; }; class Clock_core { public: Clock_core(const char*); protected: Interactor* Interior(); virtual void SetTime(); virtual void SetAlarm(); virtual void Snooze(); protected: Picture* _clock; SF_Polygon* _hour_hand; SF_Rect* _min_hand; Line* _sec_hand; };

  8. Generation Gap: Consequences • The Good • Modifications/Implementations are decoupled from generated code. • CoreClass and ExtensionClass may be developed and tested independantly. • The Bad • Doubles the number of classes. • Changes to interfaces in the tool must be reflected in the Extension. • The Ugly • Integration into inheritance may be difficult.

  9. Generation Gap: Related Pattern • Use of other patterns such as Template Method, Factory methods, or Strategy Patterns may serve to make generated code more flexible and reusable.

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