In Swedish. Mitt försök att provocera fram lite diskussion på Javaforum 2011-Q2.

2. Clean Code

3. This work by Fredrik Wendt is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License http://creativecommons.org/licenses/by-nc-sa/3.0/

6. Coding Dojo / User Group JDojo@Gbg

7. How is it even possible for code to be this bad?

9. Hudson class is untestable Singleton

10. Konstruktorn anropar en metod som hämtar singleton-instansen och anropar en metod på den.

11. Hudson extends Node, men Node använder instansmetoder på Hudson

13. Writes advanced code

15. Maintainable code

16. 'Clarity is king'

17. String lowerCaseUrl OfCurrentPage // lowercase url http://www.slideshare.net/JandV/clean-code-summary

18. Clean Code Book Comparison http://blog.xebia.com/2009/01/clean-code-vs-implementation-patterns/

19. Vad är Clean Code?

20. int d; // elapsed time in days

21. int d; // elapsed time in days int elapsedTimeInDays;

22. int d; // elapsed time in days int elapsedTimeInDays; int daysSinceCreation;

23. int d; // elapsed time in days int elapsedTimeInDays; int daysSinceCreation; int fileAgeInDays;

24. public List<int[]> getThem() { List<int[]> list1 = new ArrayList<int[]>(); for (int[] x : theList) if (x[0] == 4) list1.add(x); return list1; }

25. public List<int[]> getThem() { List<int[]> list1 = new ArrayList<int[]>(); for (int[] cell : gameBoard ) if ( cell [ STATUS_VALUE ] == FLAGGED ) list1.add( cell ); return list1; }

26. public List<int[]> getFlaggedCells () { List<int[]> flaggedCells = new ArrayList<int[]>(); for (int[] cell : gameBoard) if (cell[STATUS_VALUE] == FLAGGED) flaggedCells .add(cell); return flaggedCells ; }

27. public List< Cell > getFlaggedCells() { List< Cell > flaggedCells = new ArrayList< Cell >(); for ( Cell cell : gameBoard) if ( cell.isFlagged() ) flaggedCells.add( cell ); return flaggedCells; }

28. Clean code always looks like it was written by someone who cares

29. Clean code always looks like it was wrtten by somone who craes

30. Readable Maintainable Changeable

31. Agile Manifesto Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation Responding to change over following a plan

33. Read able?

34. ~90 % av din tid är läsning Vad händer om du dubblar skrivtiden , och därmed halverar lästiden ?

35. public class Part { private String m_dsc; // The textual description void setName(String name) { m_dsc = name; } } public class Part { private String description; void setDescription(String description) { this.description = description; } }

37. Din kollega

38. Du själv someone who cares

39. Hur ska du skriva kod då?

40. DRY - Don't Repeat Yourself YAGNI - You Ain't Gonna Need It

41. small

43. Pronounceable

46. Problemdomänens ord

47. Kommentarer

48. Kodformatering!

49. Don't talk to strangers http://www.ccs.neu.edu/research/demeter/demeter-method/LawOfDemeter/paper-boy/

50. public class PaperBoy { private Wallet myWallet; ... public void chargeCustomer(Customer customer) { Collection<Bill> payment = customer.getPayment(5) myWallet.add(payment); } } Law of Demeter

51. public class PaperBoy { private Wallet myWallet; ... public void chargeCustomer(Customer customer) { Wallet wallet = customer.getWallet(); Collection<Bill> bills = wallet.getBills(); Collection<Bill> payment = extract(5, bills); myWallet.add(payment); // or bills? } } Law of Demeter

52. public class CareTaker { private Dog dog; ... public void walkTheDog(){ dog.walk(); dog.stop(); // tree or grass etc dog.doYourThing(); ... } } Dog's Legs

53. public class CareTaker { private Dog dog; ... public void walkTheDog(){ for (Leg leg : dog.getLegs()) leg.move(); for (Leg leg : dog.getLegs()) leg.stopMoving(); dog.brain.urinationCenter.releaseUrge(); ... } } Dog's Legs

54. Law of Demeter More formally, the Law of Demeter for functions requires that a method M of an object O may only invoke the methods of the following kinds of objects: 1. O itself 2. M's parameters 3. any objects created/instantiated within M 4. O's direct component objects 5. a variable, accessible by O, in the scope of M

55. Boy Scout Rule Leave the campground cleaner than you found it.

56. The only valid measurement of code quality WTFs / minute

57. Diskussion Kodkvalitet och retrospectives Smart vs Professional Skriva för mottagaren swenug vs JavaForum swejug?

58. Kod utan test Legacy Code

60. Fixa ev buggar som testen plockar fram i ljuset

61. ”Make it right”

63. Fixa ev buggar som testen plockar fram i ljuset

64. ”Make it right” – refactor!

66. refaktoreras inte

67. ändras gärna inte av någon annan än den som skrev koden senaste dygnen

68. är en ryggsäck

74. ”Lösningen”?

75. Diskussion