Advanced OOP in Elixir

https://github.com/wojtekmach/oop

Transcript

1. Advanced OOP in Elixir Wojtek Mach @wojtekmach @wojtekmach
2. import OOP
3. import OOP class Person do var :name end
4. import OOP class Person do var :name end joe = Person.new(name: "Joe") robert = Person.new(name: "Robert")
5. import OOP class Person do var :name end joe = Person.new(name: "Joe") robert = Person.new(name: "Robert") joe.name() # => "Joe" robert.name # => "Robert"
6. import OOP class Person do var :name def say_hello_to(who) do IO.puts("#{this.name}: Hello, #{who.name}") end end joe = Person.new(name: "Joe") robert = Person.new(name: "Robert") joe.name() # => "Joe" robert.name # => "Robert" joe.say_hello_to(robert) # => Joe: Hello, Robert
7. import OOP class Person do var :name def say_hello_to(who) do IO.puts("#{this.name}: Hello, #{who.name}") end end joe = Person.new(name: "Joe") robert = Person.new(name: "Robert") joe.name() # => "Joe" robert.name # => "Robert" joe.say_hello_to(robert) # => Joe: Hello, Robert this.name
8. joe = Person.new(name: "Joe") joe.set_name("Hipster Joe") # => :ok joe.name # => "Hipster Joe"
9. Q: How does it work?

10. Q: How does it work?
 A: You don’t want to know.
11. Q: How does it work?
 A: Macros.
12. some FP programmer: „this is bad code”

13. Perhaps it’s not that bad…

14. Q: What’s worse than OOP?

15. Q: What’s worse than OOP?
 A: OOP with inheritance.
16. class Shape do var :x var :y end
17. class Shape do var :x var :y end class Rectangle < Shape do var :width var :height def area do this.width * this.height end end
18. class Shape do var :x var :y end class Rectangle < Shape do var :width var :height def area do this.width * this.height end end class Square < Rectangle do def area do :math.pow(this.width, 2) end end
19. Perhaps it’s not that bad…

20. Q: What’s worse than OOP with inheritance?

21. Q: What’s worse than OOP with inheritance?
 A: OOP with multiple inheritance.
22. class Human do end
23. class Human do end class Spider do end
24. class Human do end class Spider do end class Spiderman < [Human, Spider] do end
25. Advanced OOP
26. class Post do end Post.new
27. class Post do end class Comment do end Post.new Comment.new
28. abstract class ActiveRecord.Base do end class Post < ActiveRecord.Base do end class Comment < ActiveRecord.Base do end Post.new Comment.new
29. abstract class ActiveRecord.Base do end class Post < ActiveRecord.Base do end class Comment < ActiveRecord.Base do end Post.new Comment.new ActiveRecord.Base.new ** (RuntimeError) cannot instantiate abstract class ActiveRecord.Base
30. abstract class ActiveRecord.Base do end abstract class ApplicationRecord < ActiveRecord.Base do end class Post < ApplicationRecord do end class Comment < ApplicationRecord do end
31. class HalfLife do end
32. class HalfLife do end class HalfLife2 < HalfLife do end
33. class HalfLife do end final class HalfLife2 < HalfLife do end
34. class HalfLife do end final class HalfLife2 < HalfLife do end class HalfLife3 < HalfLife2 do end ** (RuntimeError) cannot subclass final class HalfLife2
35. class AppleInc do end
36. class AppleInc do var :devices end apple = Apple.new(devices: ["Alice's iPhone", "Bob's iPad"]) apple.devices # => ["Alice's iPhone", "Bob's iPad"]
37. class AppleInc do private_var :devices end apple = Apple.new(devices: ["Alice's iPhone", "Bob's iPad"]) apple.devices ** (RuntimeError) Cannot access private var devices
38. class NSA do def get_data(company, _fisa_court_order \\ nil) do company.devices end end class AppleInc do private_var :devices end apple = Apple.new(devices: ["Alice's iPhone", "Bob's iPad”]) NSA.new.get_data(apple) ** (RuntimeError) Cannot access private var devices
39. class NSA do def get_data(company, _fisa_court_order \\ nil) do company.devices end end class AppleInc do friend NSA private_var :devices end apple = Apple.new(devices: ["Alice's iPhone", "Bob's iPad”])
40. class NSA do def get_data(company, _fisa_court_order \\ nil) do company.devices end end class AppleInc do friend NSA private_var :devices end apple = Apple.new(devices: ["Alice's iPhone", "Bob's iPad”]) NSA.new.get_data(apple) # => ["Alice's iPhone", "Bob's iPad"]
41. Disclaimer: Don’t run it in production. Ever.
42. Disclaimer: Don’t run it in production. Ever.
43. Thank you! @wojtekmach wojtekmach/oop