Memento pattern

Abstract: In this paper, we demonstrate the use of design patterns to develop games for mobile devices on the J2ME platform. We believe that the proposed idea will help J2ME game developers to write better re-usable code faster. We consider a single player Sudoku board game which is based on the model-view-controller architecture. The view is configured with a Game Controller Choice pattern so that different controllers can be selected. The view and the model implement the Game State Observer pattern. The Canvas drawing logic is created using the Drawing Template pattern, which ensures reusability of the board size computation as well as provides a means for the programmer to implement game specific drawing functionalities. A generic undo method is provided using the Game Memento pattern. Setting of the current display is achieved through the Change Screen pattern. We note that the use of patterns in the Sudoku game makes it possible to cater for changes without breaking up the overall architecture of the game. By considering a downgraded version of the standard Soduko game, we show that patterns allow modifications to be made without opening up too many classes. We also show how the proposed design of the Sudoku game facilitates the design of other games.

Abstract: 1.Introduction -- 2.Observer Pattern -- 3. Singleton Pattern -- 4. Proxy Pattern -- 5.Decorator Pattern -- 6. Strategy Pattern (Or, Policy Pattern) -- 7. Template Method Pattern -- 8. Prototype Pattern -- 9. Adapter Pattern -- 10. Command Pattern -- 11.Iterator Pattern -- 12. Facade Pattern -- 13. Factory Method Pattern -- 14. Memento Pattern -- 15. State Pattern -- 16. Builder Pattern -- 17. Flyweight Pattern -- 18.Abstract Factory Pattern -- 19. Mediator Pattern -- 20. Chain of Responsibility Pattern -- 21. Composite Pattern -- 22. Bridge Pattern (Or Handle/Body Pattern) -- 23.Visitor Pattern -- 24. Interpreter Pattern -- FAQ -- Reference. -Acknowledgements -- About the Author.

Abstract: Classical object oriented systems require every object to be an instance of a class, and all classes to be written before the program is deployed. Some programs need exible, con gurable, dynamically extensible representations of objects, which cannot be determined in advance. The Object System pattern describes how you can build your own object system from scratch. Using the Object System pattern, you can build precisely the kind of objects you need for your application, but these objects will require more memory space and execution time than the more rigid objects supported by programming languages.

Abstract: The paper presents the importance of design pattern in reusable GIS software development.Three typical design patterns such as template method,strategy and memento pattern,which are implemented in GIS software development,are elaborated.Finally,it points out that more research of using design pattern is needed.