Building Extractable Libraries in Rails - BostonRB

Presentation for BostonRB 1/08/2013

Transcript

1. Building Extractable Libraries in Rails
2. Hello There! I’m @patricksroberts. I work at @iorahealth. I co-organize @bostonrb.
3. I am not James Daniels!
4. Nor am I Joe Grossberg (I really <3 this GIF)
5. The Duality of a Rails Developer
6. Ruby is driven by <3
7. Our best practices change with our sense of beauty
8. Our ecosystem is driven by the many ways to solve problems
9. Rails is driven by Conventions
10. Rails frees us from making many tedious decisions
11. The freedom from decisions allows us unparalleled productivity
12. /lib is a Battlefield
13. I think it can benefit from some conventions So we can ship some more code
14. Avoid the Autoload Trap Maintain explicit entry points into your library code using initializers
15. Use the Configuration Pattern Keep credentials as far away from your library code as possible
16. Isolate Interaction with your Domain Models Use the DCI pattern at the glue points of your application code
17. Avoiding the Autoload Trap
18. Rails 3 brought a wonderful convention for removing /lib from automatically being loaded on application boot...
19. ... however our first instinct is to do this: # config/application.rb # Custom directories with classes and modules you want to be autoloadable. config.autoload_paths += %W(#{config.root}/lib) Let’s try something different!
20. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ # lib/twitter_wrangler.rb require ‘twitter_wrangler/authentication’ require ‘twitter_wrangler/authorization’ module TwitterWrangler end Combined with...
21. We have created a namespace and setup a proper layout when we need to extract our code outside the application into a gem. ... in ten seconds or less :)
22. Hide Your Credentials From Your Library
23. It’s so simple to do this: # lib/twitter_wrangler.rb module TwitterWrangler OAUTH_KEY = ‘ABCDEFG1234ZXYZB2324’ end Or even this: # lib/twitter_wrangler.rb module TwitterWrangler OAUTH_KEY = ENV[‘TWITTER_KEY’] end
24. But we already have an entry point for our library code. So let’s exploit the heck out of it!
25. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
26. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
27. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
28. # config/initializers/twitter_wrangler.rb require_relative ‘../lib/twitter_wrangler’ TwitterWrangler.configure do |config| config.oauth_key = ENV[:twitter_oauth_key] end
29. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
30. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
31. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
32. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
33. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
34. # lib/twitter_wrangler/configuration.rb module TwitterWrangler class Configuration attr_accessor :oauth_key def initialize oauth_key = nil end end class << self attr_accessor :configuration end def self.configure self.configuration ||= Configuration.new yield(configuration) if block_given? end end
35. With one additional, boilerplate class we’ve established a separation of credential concerns
36. Keeping Your Domain Models Focused
37. Prescriptions Queueing Authorization Authentication Timeouts Caching BMI Appointments
38. Web App body mass index tweet called Library Authorization Twitter message Authentication Queueing
39. # lib/twitter_wrangler/roles/tweeting_patient.rb module TwitterWrangler::Roles::TweetingPatient def bmi_twitter_message “Today my BMI is #{body_mass_index} and I’m #{percent_of_body_mass_index_goal} from my goal of #{body_mass_index_goal}!” end end
40. # lib/twitter_wrangler/support/fake_patient.rb class FakePatient def body_mass_index;27;end def percent_of_body_mass_index_goal;”95%”;end def body_mass_index_goal;25;end end # spec/twitter_wrangler/roles/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { FakePatient.new } before { FakePatient.extend TweetingPatient } it ‘asserts some fantastic things’ do #GLORIOUS SPECS end end
41. # spec/twitter_wrangler/roles/tweeting_patient_spec.rb describe TweetingPatient do let(:patient) { OpenStruct.new(body_mass_index: 27, percent_of_body_mass_index_goal: “95%”, body_mass_index_goal: 25) } before { patient.extend TweetingPatient } it ‘asserts some fantastic things’ do #GLORIOUS SPECS end end
42. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate attr_reader: patient def initialize(patient) @patient = patient @patient.extend TweetingPatient end def call TwitterWranglerQueue.add @patient.bmi_twitter_message end end end
43. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate attr_reader: patient def initialize(patient) @patient = patient @patient.extend TweetingPatient end def call TwitterWranglerQueue.add @patient.bmi_twitter_message end end end
44. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate attr_reader: patient def initialize(patient) @patient = patient @patient.extend TweetingPatient end def call TwitterWranglerQueue.add @patient.bmi_twitter_message end end end
45. # lib/twitter_wrangler/bmi_twitter_update.rb module TwitterWrangler class BMITwitterUpdate attr_reader: patient def initialize(patient) @patient = patient @patient.extend TweetingPatient end def call TwitterWranglerQueue.add @patient.bmi_twitter_message end end end
46. # app/models/contexts/patient_bmi_observer.rb class PatientBmiObserver observe :patient def after_save(patient) TwitterWrangler::BMITwitterUpdate.new(patient).call @patient.extend TweetingPatient end end
47. # spec/models/patient_bmi_observer_spec.rb describe PatientBMIObserver do let(:bmi_update) { mock() } before do BMITwitterUpdate.stubs(:new).returns bmi_update bmi_update.stubs :call end it ‘sends a twitter update on mah BMI’ do # expect #call to have been called once end end
48. # spec/models/patient_bmi_observer_spec.rb describe PatientBMIObserver do let(:bmi_update) { mock() } before do BMITwitterUpdate.stubs(:new).returns bmi_update bmi_update.stubs :call end it ‘sends a twitter update on mah BMI’ do # expect #call to have been called once end end
49. Provides clear separation of Domain Model and outside code Creates isolatable tests Easy path forward for gem extraction Boilerplate :( YAGNI :(
50. Thanks!
52. Questions?