Solid foundations for Rails apps

A talk given at Railsberry, the European Rails Conference, on Apr 20, 2012.

Transcript

1. Solid foundations for Rails apps
2. Love
3. A sip of frustration
4. OOP
5. ISP SRP DRY DI Liskov Open/Closed Least surprise Tell Don’t Ask Law of Demeter Convention over Configuration Domain Language Capture
6. ISP SRP DRY DI Liskov Open/Closed Least surprise Tell Don’t Ask Law of Demeter Convention over Configuration Domain Language Capture
7. SRP
8. Change
9. class User attr_reader :name def bandwidth_usage(month) # Calculate bandwidth usage end end
10. class User attr_reader :name end class BandwidthUsage def initialize(user) user = @user end def by_month(month) # Calculate bandwidth usage end end
11. Indicators
12. class Shipment def update_destination(name, address) @first_name, @last_name = name.split(' ') @address = address end def update_last_name(name) @last_name = name.split(' ').last end end
13. class Shipment def update_destination(name, address) @first_name, @last_name = extract_names(name) @address = address end def update_last_name(name) @last_name = extract_names(name).last end private def extract_names(name) name.split(' ') end end
14. class NameParser def initialize(name) # ... end def first_name # ... end def last_name # ... end end
15. class Shipment def update_destination(name, address) name_parser = NameParser.new(name) @first_name = name_parser.first_name @last_name = name_parser.last_name @address = address end def update_last_name(name) name_parser = NameParser.new(name) @last_name = name_parser.last_name end end
16. Rails vs SRP
17. Active Record
18. Data Mapper
19. Solutions for AR
20. class User < ActiveRecord::Base include Favourites include Pictures include Organizations include Embeddable include SocialProfiles # ... end
22. class Post < ActiveRecord::Base include FigLeaf hide ActiveRecord::Base, ancestors: true, except: [Object, :init_with, :new_record?, :errors, :valid?, :save] hide_singletons ActiveRecord::Calculations, ActiveRecord::FinderMethods, # ...
23. Yet another reason
24. Is it easier to add a method to an existing class or create a new class with that method?
25. Domain Language Capture
26. Writers
27. Coders
28. Managers, Helpers etc.
29. All the layers
30. Communication
32. 1 class Tag 2 3 # ... 4 5 end
35. 1 class Tag 2 3 # ... 4 5 end
36. Confusion
37. Unify naming, stay in sync
38. DRY
39. Model attributes, Partials, Routes
40. WET?
42. Knowledge
43. Comments
44. # Concatenates the salt with the password salt + password
45. # Concatenates the salt with the password (password + salt).hash
46. class User attr_accessor :admin end
47. user.admin = true
48. Name the business process
49. class User attr_accessor :admin def grant_admin_privileges @admin = true end end
50. class GrantsAdminPrivileges def initialize(user) @user = user end def execute @user.admin = true end end
51. SRP DLC DRY
52. @mariuszlusiak