Your First Legacy Codebase

So you've just graduated from a bootcamp and you're starting your first real job in software development. You've got several Rails apps under your belt and you're excited to get started. But few jobs offer the opportunity to build new apps; it's much more likely that you will be part of a team charged with maintaining and growing a legacy application. How can you get started working on an aging codebase when the sum of your experience so far was with greenfield apps?

Transcript

1. Your First Legacy Codebase Coraline Ada Ehmke @CoralineAda
2. Congratulations!
3. Green fields lay behind you.
4. A twisted legacy awaits.
5. Who am I?
6. Code Witch
7. Long-Time Rubyist
8. where.coraline.codes
9. @CoralineAda
10. Contributor Covenant
11. Senior Engineer
12. Notorious SJW
13. Legacy Codebases
14. A large, unwieldy,
 pre-existing code base.
15. A code base so large 
 that it’s difficult to hold
 in your head all at once.
16. Code whose creators have moved on to other things.
17. Code that represents a 
 significant investment.
18. Code that is essential to 
 the company making money.
19. Code that can’t just be
 “burned down”.
20. The Ultimate Legacy Application
21. World’s Largest Rails App?
22. Canvas LMS
23. $ find . -type f | wc -l 11687
27. Legacy Architecture
28. 1990’s: The Age of the Architect
29. Detailed Requirements
30. Architecture Diagrams
31. Object Models
32. Very Thorough
33. Painfully Slow…
34. 2010’s: The Age of the Cowboy Coder
35. Evolutionary
36. Fluid
37. Undocumented
38. Easily Influenced
39. Opinionated
40. Major Obstacles to Understanding
41. Older Frameworks
42. Complexity
43. Lack of Cohesion
44. Inconsistency
45. God Models
46. Custom Gems
47. Monkey Patches
48. A Strategy for Understanding
49. The OODA Loop
50. Observe
51. Orient
52. Decide
53. Act
54. Observation
55. #{Rails.root}/docs/
56. # comments
57. Wiki
58. Architecture 
 decision records
59. Pull requests
60. Tests
61. $ rspec spec/ --format documentation Membership determines its upgradeability calculates its expiration in days detects when it has expired detects when it is expiring soon Finished in 0.01401 seconds 12 examples, 0 failures
62. Read the Code
63. Orientation
64. The Problem
65. Terms of Art
66. Patterns
67. People
68. Read Routes In
70. Decision
71. Plan a Refactor
72. Explore Inheritance
73. Uncover Modules
74. Untangle Gems
75. Understand Relationships
79. Go Exploring
81. Seek the Truth
83. def hours_occupied(date) if availability = get_work_hours(date) focus = "work" elsif availability = get_family_hours(date) focus = "family" elsif availability = get_friend_hours(date) focus = "friends" end end
84. def hours_occupied(date) if availability = get_work_hours(date) focus = "work" elsif availability = get_family_hours(date) focus = "family" elsif availability = get_friend_hours(date) focus = "friends" end end
86. def hours_occupied(date) if availability = get_work_hours(date) focus = "work" elsif availability = get_family_hours(date) focus = "family" elsif availability = get_friend_hours(date) focus = "friends" end end
88. def hours_occupied(date) if availability = get_work_hours(date) focus = "work" elsif availability = get_family_hours(date) focus = "family" elsif availability = get_friend_hours(date) focus = "friends" end end
90. Action
91. Branch
92. $ git branch -b refactor_user
93. Be Godzilla
94. Pry
95. 36: def self.create_or_update(opts={}) 37: opts = opts.with_indifferent_access 38: content = opts.delete(:content) 39: user = opts.delete(:user) 40: return nil unless user && content 41: => 42: require ‘pry’; binding.pry 43: pry> user => #<User:0x007fdcd9008828 @first_name=“Coraline">
96. Repeat the Cycle
98. Remember the goal.
99. Keep at it.
100. Pair up.
101. Believe in yourself.
102. Go write some code!
103. Thanks! Coraline Ada Ehmke @CoralineAda