Refactoring Workshop (Rails Pacific 2014)
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This document summarizes a refactoring workshop about improving code quality through refactoring. It discusses techniques like extracting logic from controllers into models, replacing long methods with method objects, using service objects to separate concerns, and implementing form objects to clean up forms. Examples are provided for each technique.
Refactoring Workshop (Rails Pacific 2014)
- 1. REFACTORING WORKSHOP Bruce Li @ Rails Pacific 2014 Please clone this repo https://github.com/ascendbruce/refactoring-workshop run bundle install and Check your ruby version
- 2. ABOUT ME • Li, Po-Chun a.k.a. Bruce Li • Work at Techbang • http://ascendbruce.logdown.com/ • @BruceToyRoom, @techbangtech
- 3. REFACTORING is important • Reduce maintenance cost • Technical debt is not about technology. It’s about people • programmer happiness is very important
- 4. TEST COVERAGE is important • Confident in changes • Code School, TeaLeaf are good start • SimpleCov and CodeClimate can make you happier while repairing test cases
- 5. PRY is useful • gem "pry-rails" gem "pry-byebug" # or pry-debugger for ruby 1.9 • binding.pry # to entering debug mode • Commands: next, step, break, continue, exit • It’s all you need at first
- 6. COMMENTS IN CODE is bad (in some cases) • Ideally, code should describe itself. • Out-dated comments are worser than none. It’s actively misleading. • Comments is helpful for providing additional information or link to issue tracking history.
- 7. 1. INTENTION REVEALING METHOD • Add comments if code need it. • Transform comments into methods. • Comments are now code. Code describes itself.
- 15. 2. MOVE MODEL LOGIC INTO THE MODEL • Move the logic, which belongs to model, into the model • instance variable should change to self in model
- 16. class ProjectsController def new # @#$^$%&#%&*#$%& @project = Project.new ! ! @project.do_ooxx @project.xxoo = "xxoo" # &*%^&@#$! end end class Project ! ! ! ! end def do_something ! ! end
- 17. class ProjectsController def new # @#$^$%&#%&*#$%& @project = Project.new @project.do_something ! ! # &*%^&@#$! end end class Project ! ! ! ! end def do_something ! ! end @project.do_ooxx @project.xxoo = "xxoo"
- 18. class ProjectsController def new # @#$^$%&#%&*#$%& @project = Project.new @project.do_something ! ! # &*%^&@#$! end end class Project ! ! ! ! end def do_something ! ! end @project.do_ooxx @project.xxoo = "xxoo"
- 19. class ProjectsController def new # @#$^$%&#%&*#$%& @project = Project.new @project.do_something do_ooxx self.xxoo = "xxoo" ! ! # &*%^&@#$! end end class Project ! ! ! ! end def do_something ! ! end
- 20. 3. REPLACE METHOD WITH METHOD OBJECT • Create a class with same initialization arguments as BIG method • Copy & Paste the method's body in the new class, with no arguments • Replace original method with a call to the new class • Apply "Intention Revealing Method" to the class
- 21. class OriginMethods def a_fat_method ! ! ! ! end end # $%@ + ($@# / ^%) # && ^ %& * #%%^ # wtf # and 100 lines...
- 22. class NewMethods def perform end end class OriginMethods def a_fat_method ! ! ! ! end end # $%@ + ($@# / ^%) # && ^ %& * #%%^ # wtf # and 100 lines...
- 23. class NewMethods def perform ! ! ! ! end end # $%@ + ($@# / ^%) # && ^ %& * #%%^ # wtf # and 100 lines... class OriginMethods def a_fat_method ! ! ! ! end end
- 24. class NewMethods def perform ! ! ! ! end end # $%@ + ($@# / ^%) # && ^ %& * #%%^ # wtf # and 100 lines... class OriginMethods def a_fat_method ! ! ! ! end end NewMethods.new.perform
- 25. class NewMethods ! ! ! ! def perform File.open(??????????) # ... end end ! class OriginMethods def a_fat_method(file_name) NewMethods.new.perform end end ?
- 26. class NewMethods ! ! ! ! def perform File.open( ) # ... end end ! class OriginMethods def a_fat_method(file_name) NewMethods.new end end
- 27. class NewMethods ! ! ! ! def perform File.open( ) # ... end end ! class OriginMethods def a_fat_method(file_name) NewMethods.new end end (file_name).perform
- 28. class NewMethods ! ! ! ! def perform def initialize(file_name) @file_name = file_name end File.open( ) # ... end end ! class OriginMethods def a_fat_method(file_name) NewMethods.new end end (file_name).perform
- 29. class NewMethods ! ! ! ! def perform def initialize(file_name) @file_name = file_name end @file_name File.open( ) # ... end end ! class OriginMethods def a_fat_method(file_name) NewMethods.new end end (file_name).perform
- 30. 4. SERVICE OBJECT • If we add new functionality to an object and: • It couples to a new dependency • It loses cohesion • Testing gets harder and slower
- 31. 4. SERVICE OBJECT • If it's a domain concept, it's an Object. If it's only an algorithm (no state) we call it a Service. • Delegate to the Service Object
- 32. 5. FORM OBJECT • accepts_nested_attributes_for is hard to track • Making very different forms for the same object is a pain. The model is messed up
- 33. 5. FORM OBJECT • include ActiveModel::Model • Set attr_reader for related models • Set attr_accessor for accepted fields • Add validators (ActiveModel::Model will take care of validation and errors) • Define persisted? method (false for create, true for update form) • Add initialize, save, update etc… if needed
- 34. REFERENCE • Crisp's Blog - Good and Bad Technical Debt • RailsCasts - Form Objects • 7 Patterns to Refactor Fat ActiveRecord Models