1. WARNING These slides are not optimized for printing or exam preparation. These are for lecture delivery only. These slides are made for PowerPoint 2010. They may not show up well on other PowerPoint versions. You can download PowerPoint 2010 viewer from here.here These slides contain a lot of animations. For optimal results, watch in slideshow mode.

3. Design (a)

5. Design (b)

7. Design (c)

15. i.Book copies in a library ii.TV drama episodes iii.Video copies in a rental shop

16. i.Book copies in a library ii.TV drama episodes iii.Video copies in a rental shop

17. i.Book copies in a library ii.TV drama episodes iii.Video copies in a rental shop  

18. i.Book copies in a library ii.TV drama episodes iii.Video copies in a rental shop   Recurring tasks in a schedule

19. i.Book copies in a library ii.TV drama episodes iii.Video copies in a rental shop Recurring tasks in a schedule

20. Déjà vu: Using patterns to solve recurring problems CS2103/T, Lecture 8, Part 1, [Oct 11, 2013]

21. Déjà vu: Using patterns to solve recurring problems

22. experience Déjà vu: Using patterns to solve recurring problems

23. experience … is what you get when you didn’t get what you wanted.

24. … is valuable. experience

25. … is too costly. experience Learning from

26. experience Learning from Note to self: never volunteer to be the headstand guy

27. experience Learning from Patterns

29. Context: Multiple stock items of same TV model Problem: Same data (but not all) shared among stock items of the same model. Solution: Represent TV model and TV stock item as different classes.

30. Context: Multiple stock items of same TV model Problem: Same data (but not all) shared among stock items of the same model. Solution: Represent TV model and TV stock item as different classes. i.Stock items ii.Book copies in a library iii.TV drama episodes iv.… i.Stock items ii.Book copies in a library iii.TV drama episodes iv.…

31. Context: Multiple stock items of same TV model Problem: Same data (but not all) shared among stock items of the same model. Solution: Represent TV model and TV stock item as different classes.

32. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes.

33. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. > *

34. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. > *

35. * TVModel TVStockItem * BookTitle BookCopy * Lesson LessonDelivery *

36. > * TVModel TVStockItem * BookTitle BookCopy * Lesson LessonDelivery *

37. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. Name: Abstraction Occurrence Pattern > *

38. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. Name: Abstraction Occurrence Pattern > * [An elegant solution to a recurring problem]

39. Name: Abstraction Occurrence Pattern Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. > * [An elegant solution to a recurring problem]

40. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. Name: Abstraction Occurrence Pattern > *

41. * Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes. > * Show off ! … for that, I used the Name: Abstraction Occurrence Pattern

42. Patterns = a high-level vocabulary

43. Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction.

44. [A stupid solution to a recurring problem] Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes.

45. [A stupid solution to a recurring problem] Context: Multiple occurrences of some abstraction Problem: Same data (but not all) shared among occurrences of the same abstraction. Solution: Represent abstraction and occurrences as different classes.

46. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

48. Context: one-and-only-one object, shared among others

49. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Context: one-and-only-one object, shared among others Problem: how to avoid multiple objects?

50. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Logic - Logic( ) + getInstance( ) : Logic Solution:

51. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Logic - theOne : Logic - Logic( ) + getInstance( ) : Logic Solution:

52. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Logic - theOne : Logic - Logic( ) + getInstance( ) : Logic public static Logic getInstance(){ if (theOne == null) theOne = new Logic(); return theOne; } public static Logic getInstance(){ if (theOne == null) theOne = new Logic(); return theOne; } //somewhere else in the system… Logic m = Logic.getInstance(); //instead of … Logic m = new Logic(); //somewhere else in the system… Logic m = Logic.getInstance(); //instead of … Logic m = new Logic(); Solution:

53. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Make everything static instead? a)OO ↓ b)Testability ↓ Logic UI LogicStub

54. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

55. Logic - theOne : Logic - Logic( ) + getInstance( ) : Logic public static Logic getInstance(){ if (theOne == null) theOne = new Logic(); return theOne; } public static Logic getInstance(){ if (theOne == null) theOne = new Logic(); return theOne; } //somewhere else in the system… Logic m = Logic.getInstance(); //instead of … Logic m = new Logic(); //somewhere else in the system… Logic m = Logic.getInstance(); //instead of … Logic m = new Logic();

56. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer How many classes in your project can benefit from this pattern? a. None b. Only 1 c. Only 2 d. Only 3 e. 4 or more single {a|b|c|d|e} e.g. single c single {a|b|c|d|e} e.g. single c 77577

57. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

58. ATD TextUI Logic

59. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer ATD TextUI MSLogic Logic

60. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer >

61. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Edit Sort Delete

62. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

64. Data objects UI elements Create/ edit/ delete/read

65. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Data objects Create/ edit/ delete/read UI elements VIEW MODEL CONTROLLER

66. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Data objects Create/ edit/ delete/read UI elements VIEW MODEL CONTROLLER

67. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

68. Paparazzi Celebrity

69. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Paparazzi Celebrity

70. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Paparazzi Celebrity

71. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer Celebrity Paparazzi

72. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer ListUI Data SummaryUI = Observers AddUI = Observed Celebrity Paparazzi

73. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer > Observer > Observer ListUI update( ) Data +addViews(Observer) -notifyUIs( ) +addViews(Observer) -notifyUIs( ) * SummaryUI update( ) :Data :Observer = Observers AddUI = Observed

74. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer > Observer > Observer > update( ) > +add(Observer) -notifyObservers( ) +add(Observer) -notifyObservers( ) * > update( )

75. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer

76. Where? → Learning → Applying

79. Which way do I face? Window or the TV? Darn…

80. Where? → Learning → Applying

81. Christopher Alexander

82. Where? → Learning → Applying Abstraction occurrence  Analysis patterns Singleton  Design patterns MVC  Architectural patterns ….  Testing patterns ….  Project management patterns

83. Where? → Learning → Applying Abstraction occurrence  Analysis patterns Singleton  Design patterns MVC  Architectural patterns ….  Testing patterns ….  Project management patterns

84. Where? → Learning → Applying

86. Creational: Abstract Factory Builder Factory Method Prototype Singleton Creational: Abstract Factory Builder Factory Method Prototype Singleton Structural: Adapter Bridge Composite Decorator Façade Flyweight Proxy Structural: Adapter Bridge Composite Decorator Façade Flyweight Proxy Behavioral : Chain of Responsibility Command Interpreter Template Method Iterator Memento State Visitor Mediator Observer Strategy Behavioral : Chain of Responsibility Command Interpreter Template Method Iterator Memento State Visitor Mediator Observer Strategy GoF patterns

87. Where? → Learning → Applying

88. So many patterns, so little time…

89. Where? → Learning → Applying So many patterns, so little time…

90. Where? → Learning → Applying So many patterns, so little time…

91. Where? → Learning → Applying Can apply Singleton in your project?

92. Where? → Learning → Applying

94. Part 1 - Déjà vu: Using patterns to solve recurring problems.

95. 1. Abstraction occurrence 2. Singleton 3. Façade 4. Command 5. MVC 6.Observer 7. …… [by next tutorial]

96. What are the negative consequence of applying the façade pattern? a. Extra code. b. Slower performance. c. Both of the above. d. No negative consequences. negative {a|b|c|d} e.g. negative c negative {a|b|c|d} e.g. negative c 77577