Ruby's Inner Beauty 2.0

Presented at Codemash 2016.

Transcript

1. RUBY'S INNER BEAUTY ALEX BURKHART - @SATERUS
2. SYNTAX
3. SYNTAX VS SEMANTICS
4. SEMANTICS VS IMPLEMENTATION
5. INTERPRETED
6. PARSING VS EXECUTION
7. PARSE A LINE 2 + 5 * 10 2 + (5 * 10) (2 + (5 * 10))
8. WALK THE TREE 2 + 5 * 10 2 + (5 * 10) (2 + (5 * 10)) (2 + (50)) (2 + 50)
9. EVALUATE THE TREE 2 + 5 * 10 2 + (5 * 10) (2 + (5 * 10)) (2 + (50)) (2 + 50) (52) 52
10. RUBY'S PARSER TRICKS
11. HUMAN READABLE NUMBERS error_prone = 1000000000 super_easy = 1_000_000_000 if error_prone != super_easy raise ProgrammerError.new("Looks like you made a typo!") end
12. ARRAY SYNTAX a1 = [1,2,3] a2 = Array.new(1,2,3) a1 == a2 # => true
13. STRING SYNTAX s1 = "syntactic sugar" s2 = 'syntactic sugar' s3 = String.new("syntactic sugar") [s1, s2, s3].uniq.one? # => true
14. ARRAY OF WORDS SYNTAX words1 = %w| array of strings | words2 = ["array", "of", "strings"] sym1 = %i( array of symbols ) sym2 = [:array, :of, :symbols]
15. ESCAPING STRING SYNTAX s1 = "\"Don't forget to escape your quotes\" -Alex" s2 = '"Don\'t forget to escape your quotes -Alex' s3 = %Q{"Don't forget to escape your quotes" -Alex} s4 = %q{"Don't forget to escape your quotes" -Alex} [s1, s2, s3, s4].uniq.one? # => true
16. ESCAPING REGEXP r1 = /^(\/foo\/|\/bar\/)/ r2 = Regexp.new("^(/foo/|/bar/)") r3 = %r_^(/foo/|/bar/)_ [r1, r2, r3].uniq.one? # => true
17. SHORTHAND SYNTAX square = Proc.new { |x| x * x } square.call(2) # => 4 cube = ->(y){ y * y * y } cube.call(2) # => 8 cube.class == Proc # => true
18. HASH SYNTAX h1 = { a: 10 } h2 = { :a => 10 } h3 = Hash.new h3[:a] = 10 h1 == h2 == h3 # => true
19. FAKE SYNTAX params = { category: 'ruby' } params[:category] # => 'ruby'
20. FAKE SYNTAX params = { category: 'ruby' } params[:category] # => 'ruby' class Hash def [](key) fetch(key, nil) end end
21. INSTANCE VARIABLE ACCESS class Coffee def initialize(size, roast) @size = size @roast = roast end def to_s "#{@size} cup of #{@roast} roast" end end pry> Coffee.new('large', 'light').to_s => "large cup of light roast"
22. INSTANCE VARIABLE ACCESS class Coffee def initialize(size, roast) instance_variable_set(:@size, size) instance_variable_set(:@roast, roast) end def to_s size = instance_variable_get(:@size) roast = instance_variable_get(:@roast) "#{size} cup of #{roast} roast" end end pry> Coffee.new('large', 'light').to_s => "large cup of light roast"
23. BasicObject#send
24. MESSAGE PASSING cup = Coffee.new('large', 'light') cup.to_s == cup.send(:to_s)
25. MESSAGE PASSING W/ ARGS client = ApiClient.new client.get('/foo', page: 2) client.send(:get, '/foo', { page: 2 })
26. EVERYTHING IS A MESSAGE 12 + 8 12.send(:+, 8) operators = [:+, :-, :/] operators.send(:<<, :*)
27. ASSIGNMENT class Todo attr_accessor :state def initialize(title) @title = title @state = :pending end end ruby_talk = Todo.new("Present Ruby's Inner Beauty at Codemash") ruby_talk.state = :in_progress
28. ASSIGNMENT METHODS class Todo attr_reader :state def initialize(title) @title = title @state = :pending end def state=(state) @state = state end end ruby_talk = Todo.new("Present Ruby's Inner Beauty at Codemash") ruby_talk.state = :in_progress
29. ASSIGNMENT METHODS class Todo attr_reader :state def initialize(title) @title = title @state = :pending end def state=(state) @state = state end end ruby_talk = Todo.new("Present Ruby's Inner Beauty at Codemash") ruby_talk.state=(:in_progress)
30. ASSIGNMENT VIA MESSAGES class Todo attr_reader :state def initialize(title) @title = title @state = :pending end def state=(state) @state = state end end ruby_talk = Todo.new("Present Ruby's Inner Beauty at Codemash") ruby_talk.send(:state=, :in_progress)
31. ABSOLUTELY EVERYTHING IS A MESSAGE class Todo attr_reader :state def initialize(title) @title = title @state = :pending end def state=(state) @state = state end end ruby_talk = Todo.send(:new, "Present Ruby's Inner Beauty at Codemash") ruby_talk.send(:state=, :in_progress)
32. Class#new class Class def new(*args) instance = allocate instance.initialize(*args) instance end def allocate Heap.malloc(self) # gross simplification end end Coffee.send(:new, 'medium', 'dark')
33. Class#new IS JUST A METHOD
34. include Celluloid # Class methods added to classes which include Celluloid module ClassMethods # Create a new actor def new(*args, &block) proxy = Cell.new(allocate, behavior_options, actor_options).proxy proxy._send_(:initialize, *args, &block) proxy end end
35. ASYNC MESSAGE PASSING class AsyncSpammer include Celluloid def deliver_spam(address) sleep(1) puts "spamming #{address.inspect}" end end worker = AsyncSpammer.new # => #<Celluloid::CellProxy(AsyncSpammer:0x3fd351810484)> worker.async.deliver_spam('your_email@example.com') # => nil # => spamming "your_email@example.com"
36. THAT'S PRETTY CLASSY
37. class KEYWORD class Todo def initialize(title) @title = title @state = :pending end def to_s "#{@state}: #{@title}" end end Todo.new('Introduce class Keyword')
38. Class::new
39. Class::new Todo = Class.new(Object) do def to_s "#{@state}: #{@title}" end end Todo.send(:new, "Reveal the `new` class method on Class")
40. REOPENING CLASSES Todo ||= Class.new(Object) Todo.class_eval do def state=(state) instance_variable_set(@:state, state) end end t2 = Todo.send(:new, 'Reopen Todo Class') t2.send(:state=, :in_progress)
41. WHAT THE def?
42. def DEMYSTIFIED class Todo define_method(:state=) do |new_state| @state = new_state end end t2 = Todo.new('Breakdown def keyword') t2.state = :in_pieces
43. def DEMYSTIFIED Todo ||= Class.new Todo.class_eval do define_method :state= do |new_state| instance_variable_set(:@state, new_state) end end t2 = Todo.send(:new, 'Breakdown def keyword') t2.send(:state=, :in_pieces)
44. attr_reader attr_writer attr_accessor
45. A BETTER METHOD MAKING MACHINE Class.class_eval do define_method(:better_reader) do |name| define_method(name) do instance_variable_get("@#{name}") end end end Todo.class_eval { better_reader :title } t = Todo.new("Reimplement attr_reader") t.title # => "Reimplement attr_reader"
46. PRACTICALLY A MONEY MAKING MACHINE Class.class_eval do define_method(:better_writer) do |name| define_method("#{name}=") do |val| instance_variable_set("@#{name}", val) end end end Todo.class_eval { better_writer :title } t = Todo.new("Reimplement attr_writer") t.title = "A much better writer..." t.title # => "A much better writer..."
47. PRIVATE METHODS class TodoList def to_s unfinished_tasks.join("\n") end private def unfinished_tasks @todos.reject(&:completed?) end end
48. MODULE PUBLICITY Module#define_method(name, &impl) => sym Module#public(*syms) Module#protected(*syms) Module#private(*syms)
49. PRIVATE METHODS TodoList ||= Class.new TodoList.class_eval do private( define_method(:unfinished_tasks) do @todos.reject(&:completed?) end ) end
50. RECEIVERLESS METHODS class MonthlyReport def print_as_table puts header rows.each do |row| puts row end puts footer end end
51. KERNEL module Kernel def puts(strs*) # ... end end Object.include(Kernel)
52. LOCAL VARIABLES HOW DO THEY WORK?
53. LOCAL VARIABLES class Todo def state=(new_state) previous_state = @state puts "Transitioning from #{previous_state} to #{new_state}" @state = new_state end end
54. Kernel#binding class Todo def state=(new_state) previous_state = @state binding.local_variables # => [:new_state, :previous_state] puts "Transitioning from #{previous_state} to #{new_state}" binding.eval('new_state') == new_state # => true @state = new_state end end
55. LOCAL VARIABLES ARE SYNTAX SHORTCUTS! class Todo def state=(new_state) @state = binding.local_variable_get(:new_state) end end
56. REMOVING THE SYNTAX Todo.class_eval do define_method :state= do |new_state| instance_variable_set(:@state, binding.local_variable_get(:new_state)) end end
57. NEARLY A LISP (Todo.class_eval { (define_method(:state=) { |new_state| (instance_variable_set(:@state, (binding.local_variable_get(:new_state))))})})
58. LOCAL CONTEXT
59. SELF class Todo def get_binding binding end def get_self binding.eval('self') end end t = Todo.new t.get_binding # => #<Binding:0x007fa6a485df20> t.get_self # => #<Todo:0x007fa6a485df20>
60. CHANGE SELF Todo.class_eval do # self == Todo class end t2 = Todo.new("Change execution contexts") t2.instance_eval do # self == instance of Todo end
61. SELF IS THE END?
62. SELF IS THE END SYNTAX TOO!
63. EVAL + BINDING => SUPERMETA class SuperMeta def initialize(data) @data = data end def instanze_eval(str) eval(str, self.send(:binding)) end end sm = SuperMeta.new(too_far: true) sm.instanze_eval('puts "Too far? #{self.instance_variable_get(:@data)}"') # => Too far? {:too_far=>true}
64. BINDING IS THE END
65. SMALL LANGUAGE
66. SYNTAX VS SEMANTICS
67. ELEGANCE
68. RUBY IS BEAUTIFUL
69. SHAMELESS PLUG FOR Mutually Human MUTUALLYHUMAN.COM
70. THANKS! ALEX BURKHART @SATERUS Mutually Human