Design patterns – Belarus Ruby on Rails User Group 23 Feb 2013

Transcript

1. Design patterns Sergey Nartimov Brainspec https://github.com/lest twitter: @just_lest
2. About • Rails, Rubinius, Elixir contributor • Software engineer at Brainspec Sergey Nartimov Brainspec https://github.com/lest twitter: @just_lest
5. $ wc -l app/models/**/*.rb | sort -nr 5450 total 595 app/models/order.rb 434 app/models/user.rb 326 app/models/variant.rb 314 app/models/product.rb 279 app/models/invoice.rb 248 app/models/cart.rb
6. $ wc -l app/models/**/*.rb | sort -nr 5450 total 595 app/models/order.rb 434 app/models/user.rb 326 app/models/variant.rb 314 app/models/product.rb 279 app/models/invoice.rb 248 app/models/cart.rb https://github.com/drhenner/ror_ecommerce
7. https://github.com/errbit/errbit
11. A pattern is a careful description of a perennial solution to a recurring problem within a building context, describing one of the configurations that brings life to a building.
12. Ralph Johnson, Richard Helm, Erich Gamma, John Vlissides
13. Program to an interface, not an implementation. Gang of Four 1995:18
14. Favor object composition over class inheritance. Gang of Four 1995:20
15. Strategy
16. Strategy
17. Strategy
18. Strategy class Status attr_accessor :publisher def publish publisher.publish(status) end end
19. Strategy class Status attr_accessor :publisher def publish publisher.publish(status) end end class TwitterPublisher def publish(status) # ... end end class FacebookPublisher def publish(status) # ... end end
20. Strategy class Status attr_accessor :publisher def publish publisher.publish(status) end end class TwitterPublisher def publish(status) # ... end end class FacebookPublisher def publish(status) # ... end end status = Status.new status.publisher = TwitterPublisher.new status.publish
21. Decorator
22. Decorator
23. Decorator
24. Decorator class Post def publish # ... end end
25. Decorator class Post def publish # ... end end class EmailNotifier < SimpleDelegator def publish super && notify! end private def notify! # ... end end
26. Decorator class Post def publish # ... end end class EmailNotifier < SimpleDelegator def publish super && notify! end private def notify! # ... end end post = Post.new notifiable_post = EmailNotifier.new(post) notifiable_post.publish
27. Command
28. Command
29. Command class CreateProducts < ActiveRecord::Migration def up create_table :products do |t| t.string :name t.text :description t.timestamps end end def down drop_table :products end end
33. Martin Fowler
35. http://martinfowler.com/eaaCatalog/
37. Domain Model
38. Service Layer
39. https://github.com/errbit/errbit
40. https://github.com/errbit/errbit
41. Active Record
42. Data Mapper
43. DataMapper 2 FTW Dan Kubb Piotr Solnica
44. Thanks <3 Sergey Nartimov Brainspec https://github.com/lest twitter: @just_lest