Sin refactor no hay paraíso

Todos hemos tenido que lidiar alguna vez con código legado, en Idealista, la app de Android tiene ya varios años y necesitaba un poco de cariño y mimos.

En esta charla contaremos las venturas y desventuras de cómo tratar con código legado, estrategias para no sufrir (tanto), y cómo darle abrazos y besos a tu proyecto para adaptar tu código a las nuevas necesidades.

Trabajaremos sobre Android, aunque muchas de las técnicas, estrategias y consejos son aplicables también para Java (incluso para otros lenguajes)

Transcript

1. #T3chFest2017 @npatarino Nicolás Patarino @npatarino Idealista
2. #T3chFest2017 @npatarino
3. #T3chFest2017 @npatarino My journey
4. #T3chFest2017 @npatarino 2000 2010 2011 2015 2013
5. #T3chFest2017 @npatarino Spaguetti code
6. #T3chFest2017 @npatarino • The harder to understand the code, the faster it decay • Duplicated code means duplicated changes • Code could run faster, but it takes days to understand • Your code is part of a bigger story Spaguetti code
7. #T3chFest2017 @npatarino 7 What refactor is? Refactoring (noun): a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior. Refactoring (verb): to restructure software by applying a series of refactorings without changing its observable behavior.
8. #T3chFest2017 @npatarino 8 What refactor is? Refactoring (noun): a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior. Refactoring (verb): to restructure software by applying a series of refactorings without changing its observable behavior.
9. #T3chFest2017 @npatarino Why refactor?
10. #T3chFest2017 @npatarino • Help the future developer, the future developer is going to be yourself • Refactor helps to understand unfamiliar code • You could find bugs. It clarifies assumptions that you’ve made • You get your patterns sense Why refactor?
11. #T3chFest2017 @npatarino How to spot a legacy coder?
12. #T3chFest2017 @npatarino
13. #T3chFest2017 @npatarino How to spot a legacy coder? YOU are the legacy coder!
14. #T3chFest2017 @npatarino Respect the previous dev
15. #T3chFest2017 @npatarino • They have done their best with their resources • Schedule Driven Development • At the time was other or no well formed architecture Respect the previous dev
16. #T3chFest2017 @npatarino
17. #T3chFest2017 @npatarino • They have done their best with their resources • Schedule Driven Development • At the time was other or no well formed architecture • Business grows faster than the app • Your current code will be legacy in a while • If there is no legacy, whom will you blame? Respect the previous dev
18. #T3chFest2017 @npatarino
19. #T3chFest2017 @npatarino Refactor or rewrite?
20. #T3chFest2017 @npatarino • It’s OK if MVPs or beginning of the project Rewrite
21. #T3chFest2017 @npatarino Rewrite
22. #T3chFest2017 @npatarino • It’s OK if MVPs or beginning of the project Problems ◦ You’ll lose some know-how ◦ No time to response to a new cool competitor’s feature ◦ Migration old to new data ◦ It could fall down in spaghetti code again Rewrite
23. #T3chFest2017 @npatarino Idealista & Android
24. #T3chFest2017 @npatarino What happened at Idealista?
25. #T3chFest2017 @npatarino Our journey
26. #T3chFest2017 @npatarino Stalk the code
27. #T3chFest2017 @npatarino Stalk the code
28. #T3chFest2017 @npatarino Stalk the code
29. #T3chFest2017 @npatarino Stalk the code
30. #T3chFest2017 @npatarino Search for architecture
31. #T3chFest2017 @npatarino Search for architecture
32. #T3chFest2017 @npatarino Add Clean Architecture Presentation Layer Model View Presenter Domain Layer Java Objects Providers Data Layer Repository Pattern Java Objects Asynchronous Layer
33. #T3chFest2017 @npatarino Do you remember?
34. #T3chFest2017 @npatarino Become to
35. #T3chFest2017 @npatarino
36. #T3chFest2017 @npatarino • Extract methods, classes • Replace types with polymorphism • Smell codes • Remove unnecessary external libraries • Immutability • ... Little refactors
37. #T3chFest2017 @npatarino Mutability
38. #T3chFest2017 @npatarino • Mutable objects are not thread-safe • Hard to parallelize • Inconsistent if you have exceptions • Not possible to cache objects • Side effects Mutability
39. #T3chFest2017 @npatarino Note - PropertyFilter
40. #T3chFest2017 @npatarino CommonFilter commonFilter = new CommonFilter(); commonFilter.setOperation(Operation.rent()); filterManager.doSomething(commonFilter); Log.d(commonFilter.getOperation()); Mutability
41. #T3chFest2017 @npatarino CommonFilter commonFilter = new CommonFilter(); commonFilter = new CommonFilter.Builder() .withTypology(commonFilter.getPropertyType()) .withWhere(commonFilter.getWhere()) .withOperation(Operation.rent()); filterManager.doSomething(commonFilter); Log.d(commonFilter.getOperation()); CommonFilter commonFilter = new CommonFilter(); commonFilter = commonFilter.with(Operation.rent()); filterManager.doSomething(commonFilter); Log.d(commonFilter.getOperation()); Mutability
42. #T3chFest2017 @npatarino Coupling
43. #T3chFest2017 @npatarino Problems • Difficulties to change libraries or implementations • Little changes were reflected into all project • Connascence Coupling
44. #T3chFest2017 @npatarino Off-topic - Alfredo Casado http://slides.com/alfredocasado-1/deck
45. #T3chFest2017 @npatarino
46. #T3chFest2017 @npatarino • Fabric • Picasso • Logging • Analytics • App Info • Firebase • ... Wrapping up
47. #T3chFest2017 @npatarino private void addImageToView(ApiAd rowElement) { Log.d(TAG, "Maradona es más grande que Pelé"); textView.setText("Time: " + System.currentTimeMillis()) Picasso.with(context) .load(rowElement.getImageUrl()) .into(thumbnail); } Wrapping up
48. #T3chFest2017 @npatarino public interface ImageLoader<T> { void load(T imageView, String url) ; } public interface Logger<T> { void d(String tag, String message) ; } public interface TimeProvider { long getCurrentTimeMillis() ; } Wrapping up
49. #T3chFest2017 @npatarino public class PicassoImageLoader implements ImageLoader<ImageView> { private final Context context; public PicassoImageLoader(Context context) { this.context = context; } @Override public void load(ImageView imageView, String url) { Picasso.with(context).load(url).into(imageView); } } Wrapping up
50. #T3chFest2017 @npatarino private void addImageToView(ApiAd rowElement) { Log.d(TAG, "Maradona es más grande que Pelé"); textView.setText("Time: " + System.currentTimeMillis()); Picasso.with(context) .load(rowElement.getImageUrl()) .into(thumbnail); } private void addImageToView(ApiAd rowElement) { logger.d(TAG, "Maradona es más grande que Pelé"); long currentTimeMillis = timeProvider.getCurrentTimeMillis(); textView.setText("Time: " + currentTimeMillis) imageLoader.load(thumbnail, rowElement.getImageUrl()); } Wrapping up
51. #T3chFest2017 @npatarino Dependency injection
52. #T3chFest2017 @npatarino public class GetTitleCommand extends Command<MoviesView> { private final GetTitlesUseCase useCase; public GetTitleCommand( MoviesView view, UseCaseProvider useCaseProvider, Presenter presenter ) { super(view); useCase = useCaseProvider.getGetTitle(); presenter.addCommand(this); } @Override public void ui(MoviesModel movies) { view.clearMovies(); view.addMovies(movies); } } Dependency injection
53. #T3chFest2017 @npatarino Consensus decision-making
54. #T3chFest2017 @npatarino Code style guidelines
55. #T3chFest2017 @npatarino
56. #T3chFest2017 @npatarino Metrics
57. #T3chFest2017 @npatarino Metrics
58. #T3chFest2017 @npatarino • If we increase the complexity, we should reduce somewhere else • Extract method / variable / class • Remove “Roberto Carlos Code” Metrics To-Do(s)
59. #T3chFest2017 @npatarino
60. #T3chFest2017 @npatarino public int getCheckId(NewAdSecondStepField field) { for (int i = 0; i < field.getPossibleValues().size(); i++) { String value = (String) field.getPossibleValues().values().toArray()[i]; if (value =! null) { if (value.equals(field.getDefaultValue())) { return 100 + i; } } } return 100; } Roberto Carlos Code
61. #T3chFest2017 @npatarino • If we increase the complexity, we should reduce somewhere else • Extract method / variable / class • Remove “Roberto Carlos Code” • SOLID, DRY (DIE), KISS, Patterns Metrics - To-Do(s)
62. #T3chFest2017 @npatarino The boy scout rule
63. #T3chFest2017 @npatarino Code Review
64. #T3chFest2017 @npatarino • Share Knowledge • Mentoring • Make consensus • Find bugs Important • Respect • Critique - Solution Code Review
65. #T3chFest2017 @npatarino Code Review
66. #T3chFest2017 @npatarino Pair programming
67. #T3chFest2017 @npatarino Cool stuff we have done
68. #T3chFest2017 @npatarino Tools Espresso
69. #T3chFest2017 @npatarino Clean framework
70. #T3chFest2017 @npatarino Git hooks
71. #T3chFest2017 @npatarino Diff request
72. #T3chFest2017 @npatarino VROK
73. #T3chFest2017 @npatarino Draw Search
74. #T3chFest2017 @npatarino Draw Search, MV(S)P Drawing Live Search Polygon Ad Selected
75. #T3chFest2017 @npatarino Draw Search, MV(S)P Drawing Live Search Polygon Ad Selected Actions • cancel() • buttonClicked() • selectAd()
76. #T3chFest2017 @npatarino Draw Search, MV(S)P Drawing Live Search Polygon Ad Selected cancel() cancel() selectAd() selectAd() cancel() cancel() cancel() buttonClicked() buttonClicked()
77. #T3chFest2017 @npatarino
78. #T3chFest2017 @npatarino It’s OK to fail
79. #T3chFest2017 @npatarino • Remove PropertyFilter It’s OK to fail
80. #T3chFest2017 @npatarino
81. #T3chFest2017 @npatarino • Remove PropertyFilter • Remove PropertyFilter (Mikado method) It’s OK to fail
82. #T3chFest2017 @npatarino Mikado method
83. #T3chFest2017 @npatarino
84. #T3chFest2017 @npatarino • Remove PropertyFilter • Remove PropertyFilter (Mikado method) • Reduce number of lines It’s OK to fail
85. #T3chFest2017 @npatarino Before - After
86. #T3chFest2017 @npatarino Before - After
87. #T3chFest2017 @npatarino • Remove PropertyFilter • Remove PropertyFilter (Mikado method) • Reduce number of lines • Test less than we should It’s OK to fail
88. #T3chFest2017 @npatarino Because we’ve learned for everyday work
89. #T3chFest2017 @npatarino • Little refactor • Strict with ourselves • Increase Automation • Think about big story • Test, test, test! (as less as possible to sleep well) • Innovate Because we’ve learned for everyday work
90. #T3chFest2017 @npatarino
91. #T3chFest2017 @npatarino
92. #T3chFest2017 @npatarino {api} Fran Pulido @FranPulidoM Victor de Francisco @vicdefran Jose del Pozo @Josedlpozo Kike Fau @KikeFau Miguel Olmedo @molmedoc Javier Aznar @JavierAznar1 Dani Jiménez @danibto Salvador Labajos @SalvatoreLabs
93. #T3chFest2017 @npatarino
94. #T3chFest2017 @npatarino You don’t need to be an excellent programmer.
95. #T3chFest2017 @npatarino You don’t need to be an excellent programmer. You need to be a good programmer with excellent habits.
96. #T3chFest2017 @npatarino We are hiring rrhh@idealista.com
97. #T3chFest2017 @npatarino Nicolás Patarino @npatarino Idealista