The document discusses several SOLID principles of object oriented design including the single responsibility principle, open/closed principle, Liskov substitution principle, interface segregation principle and dependency inversion principle. It provides examples of how to apply each principle and notes that principles are not rules and the goal is to design for people first before computers. The document concludes by listing several SOLID principles and providing additional resources on design topics.

1. Agile Object Oriented Design SOLID principles [email_address]

2. Why it is Agile?

6. ?

8. principles != rules

9. Single Responsibility Principle

10. Problem domain Conceptual model Implementation

11. Problem domain Conceptual model Implementation ? ?

13. NOooo!!

14. Book Instrument 1 * 1 1 Position value: double

15. Book Position Listener 1 BookPosNode Book Position Listener 2 Network Application position position position

16. BookPosNode AbstractBookPosNode Subscriber SnapshotProvider HeartbeatMonitor StateMachine

17. 1

18. 2

19. 3

20. 4 the rest of the class is collapsed

21. 5 the rest of the class is collapsed

22. Open/Closed Principle

23. AbstractPositionNode BookPosNode Client

24. AbstractPositionNode BookPosNode JMSNode Client PositionWatcher Add Change

25. AbstractPositionNode BookPosNode JMSNode Client PositionWatcher Add NodeV2

26. Front-end Back-end Database Change

27. Liskov Substitution Principle

31. Ellipse-circle problem rectangle-square

32. Point x, y : int #equals() #hashCode()

33. Point x, y : int #equals() #hashCode() ColorPoint color : Color #equals() #hashCode()

34. Point x, y : int #equals() #hashCode() ColorPoint color : Color #equals() #hashCode() Can't extend like this preserving equals contract (Effective Java, Item 8)

35. @IViolateLSP

36. class Dog implements ICanBark … class Button implements IClickable …

37. Interface Segregation Principle

38. <<interface>> BigService Client1 Client2 Client3

39. <<interface>> BigService <<interface>> Service1 <<interface>> Service2 <<interface>> Service3 Client1 Client2 Client3

41. BookPositionNode <<interface>> ResubscribingNode AbsPosNode StateMachine Client uses uses

42. Dependency Inversion Principle

43. Client Service client service

44. Client <<interface>> Service ServiceImpl client service

45. client service

46. Client <<interface>> Service ServiceImpl client service

47. Client <<interface>> Service ServiceImpl client service

48. client service

49. Client <<interface>> Service ServiceImpl client service api

51. S RP O CP L SP I SP D IP

52. Single Responsibility Principle

53. Open/Closed Principle

54. Liskov Substitution Principle

55. Interface Segregation Principle

56. Dependency Inversion Principle

57. What else?

58. Problem domain Conceptual model Implementation

59. F**k Design

60. Zen Coding

62. and only then for computers Code is written for people

63. REP CRP CCP ADP SDP SAP

64. UML, patterns, and more...

66. Thanks!

67. S RP O CP L SP I SP D IP

68. http://weblogs.java.net/blog/82/2003/09/02/aristotles-error-or-agile-smagile http://blog.objectmentor.com/articles/2009/01/31/quality-doesnt-matter-that-much-jeff-and-joel http://www.codinghorror.com/blog/archives/000805.html http://www.youtube.com/watch?v=2k1uOqRb0HU http://blogs.msdn.com/brada/archive/2003/10/02/50420.aspx http://www.joelonsoftware.com/articles/LeakyAbstractions.html http://www.joelonsoftware.com/items/2009/09/23.html