Why is nobody using Refinements?

From RubyConf 2015; transcript will be at http://lazyatom/refinements

Refinements have been a feature in Ruby for several years now, added as a more structured alternative to the "scourge" of monkey patching, but it seems like almost nobody is using them. My question is this: why not? Are they a bad idea? Are they broken? Or do we just not understand them?

Let's figure out once and for all what refinements are good for, and what their limitations might be, so that future generations can either use them for glory, or rightfully ignore them forevermore.

Transcript

1. module WhyIsNobody using Refinements end # lazyatom.com/refinements
2. Disclaimer This is not a sales pitch for refinements. I am not going to show you how they are amazing and will solve all your programming problems. They might be good… but also they might be bad. They might even be terrible! Using refinements might make your application implode, or make you smell really bad, or lower your credit rating, or make your cat regard you with an even stronger level of apathetic disdain. Please do not hold me responsible if use of refinements leaves you with an unexplainable rash, or an overwhelming sense of ennui. Other side effects may include: syntax itch, nil nausea, const-ipation, drowsiness, and global interpreter lockjaw.
3. What are refinements? A mechanism to change the behaviour of an object in a limited and controlled way
4. module Shouting refine String do def shout self.upcase + "!" end end end
5. module Shouting refine String do def shout self.upcase + "!" end end end class Thing using Shouting "Hello".shout # => "HELLO!" end
6. module Shouting refine String do def shout self.upcase + "!" end end end class Thing using Shouting "Hello".shout # => "HELLO!" end "Hello".shout # => NoMethodError: undefined method 'shout' for "Oh no":String
7. module TexasTime refine Time do def to_s if hour > 12 "Afternoon, y’all!" else super end end end end
8. module TexasTime refine Time do def to_s if hour > 12 "Afternoon, y’all!" else super end end end end class RubyConf using TexasTime Time.parse("12:00").to_s # => "2015-11-16 12:00:00" Time.parse("14:15").to_s # => "Afternoon, y’all!" end
9. module TexasTime refine Time do def to_s if hour > 12 "Afternoon, y’all!" else super end end end end class RubyConf using TexasTime Time.parse("12:00").to_s # => "2015-11-16 12:00:00" Time.parse("14:15").to_s # => "Afternoon, y’all!" end Time.parse("14:15").to_s # => "2015-11-16 14:15:00"
10. using ( a developer’s guide )
11. class Thing "hello".shout # => "HELLO!" end using Shouting
12. class Thing "hello".shout # => "HELLO!" end using Shouting
13. class Thing def greet "hello".shout end end Thing.new.greet # => "HELLO!" using Shouting
14. class Thing def greet "hello".shout end end Thing.new.greet # => "HELLO!" using Shouting
15. class Thing def greet "hello" end end Thing.new.greet using Shouting .shout # => NoMethodError
16. class Thing using Shouting end class Thing "hello".shout # => NoMethodError end
17. class Thing using Shouting class OtherThing "hello".shout # => "HELLO!" end end
18. class Thing using Shouting class OtherThing < Thing "hello".shout end end # => NoMethodError
19. class Thing using Shouting class OtherThing < Thing "hello".shout end end # => "HELLO!"
20. class Thing using Shouting class OtherThing "hello".shout # => "HELLO!" end end
21. class Thing using Shouting end class Thing::OtherThing "hello".shout # => NoMethodError end
22. class Thing using Shouting def run yield end end Thing.new.run do "hello".shout end # => NoMethodError
23. Lexical Scope
24. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout
25. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level
26. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level
27. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level A
28. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none A Parent Top Level
29. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none A Parent Top Level
30. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none A Parent Top Level
31. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
32. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
33. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
34. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout
35. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout # => “HELLO!”
36. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout
37. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
38. file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
39. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout
40. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting # => NoMethodError file: thing.rb class Thing using Shouting "hello".shout end "goodbye".shout
41. file: thing.rb using Shouting class Thing "hello".shout end "goodbye".shout Top Level Parent none Refinements Shouting A Parent Top Level Refinements Shouting
42. Top Level Parent none Refinements Shouting A Parent Top Level Refinements Shouting file: thing.rb using Shouting class Thing "hello".shout end "goodbye".shout
43. Top Level Parent none Refinements Shouting A Parent Top Level Refinements Shouting file: thing.rb using Shouting class Thing "hello".shout end "goodbye".shout # => “HELLO!” # => “GOODBYE!”
44. Refinements are activated in current and nested lexical scopes
45. file: thing.rb class Thing using Shouting end class Thing "hello".shout end
46. file: thing.rb class Thing using Shouting end class Thing "hello".shout end Top Level Parent none Refinements empty
47. file: thing.rb class Thing using Shouting end class Thing "hello".shout end Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
48. file: thing.rb class Thing using Shouting end class Thing "hello".shout end Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting B Parent Top Level Refinements empty
49. file: thing.rb class Thing using Shouting end class Thing "hello".shout end Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting B Parent Top Level Refinements empty
50. same class ≠ same scope
51. file: thing.rb class Thing using Shouting end class Other < Thing "hello".shout end
52. file: thing.rb class Thing using Shouting end class Other < Thing "hello".shout end Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting B Parent Top Level Refinements empty
53. class hierarchy ≠ scope hierarchy
54. different file = different scope
55. file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet
56. file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting
57. file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A
58. file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A
59. file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A
60. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet
61. Top Level Parent none Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A file: thing.rb class Thing using Shouting def greet "hello".shout end end Thing.new.greet # => “HELLO!”
62. methods are evaluated using the lexical scope at their definition
63. file: thing.rb class Thing using Shouting def run yield end end Thing.new.run do "hello".shout end # => NoMethodError
64. file: thing.rb class Thing using Shouting def run yield end end Thing.new.run do "hello".shout end Top Level Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A
65. file: thing.rb class Thing using Shouting def run yield end end Thing.new.run do "hello".shout end Top Level Refinements empty A Parent Top Level Refinements Shouting Thing#greet Lexical scope A Main#block Lexical scope Top level
66. blocks are evaluated using the lexical scope at their definition
67. Refinements use lexical scope
68. You get a new lexical scope when 1. Entering a different file 2. opening a class or module definition 3. running code from a string using “eval”
69. Refinement principles 1. activated within current and nested scopes 2. scope hierarchy is not the same as class hierarchy 3. different files get different top level scopes 4.methods are evaluated using lexical scope at their definition 5. blocks are evaluated using lexical scope at their definition
70. Let’s use refinements!
71. 1. Monkey patching
72. class String def camelize self.split("_").map(&:capitalize).join end end "ruby_conf_2015".camelize # => "RubyConf2015"
73. /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ inflector/methods.rb:261:in `const_get': wrong constant name Admin/adminHelper (NameError) from /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ inflector/methods.rb:261:in `block in constantize' from /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ inflector/methods.rb:259:in `each' from /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ inflector/methods.rb:259:in `inject' from /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ inflector/methods.rb:259:in `constantize' from /app/.bundle/gems/ruby/2.1.0/gems/activesupport-4.2.1/lib/active_support/ core_ext/string/inflections.rb:66:in `constantize' from /app/.bundle/gems/ruby/2.1.0/gems/actionpack-4.2.1/lib/ abstract_controller/helpers.rb:156:in `block in modules_for_helpers' from /app/.bundle/gems/ruby/2.1.0/gems/actionpack-4.2.1/lib/ abstract_controller/helpers.rb:144:in `map!' from /app/.bundle/gems/ruby/2.1.0/gems/actionpack-4.2.1/lib/ abstract_controller/helpers.rb:144:in `modules_for_helpers' from /app/.bundle/gems/ruby/2.1.0/gems/actionpack-4.2.1/lib/action_controller/ metal/helpers.rb:93:in `modules_for_helpers'
74. Monkey-patching Refinements breaks API expectations cannot affect distant code makes code harder to debug leaves lexical clue when active
75. 2. Managing API changes
76. # Ruby 1.9 "hello".chars # => #<Enumerator: "hello".each_char> # Ruby 2.0+ "hello".chars # => ["h", "e", "l", "l", "o"]
77. module OldChars refine String do def chars; each_char; end end end "hello".chars # => ["h", "e", "l", "l", “o"] using OldChars "hello".chars # => #<Enumerator: "hello".each_char>
78. 3. DSLs
79. describe "Ruby" do it "should bring happiness" do developer = Developer.new(uses: "ruby") developer.should be_happy end end
80. describe "Ruby" do it "should bring happiness" do developer = Developer.new(uses: "ruby") developer.should be_happy end end
81. module RSpec refine Object do def should(expectation) expectation.satisfied_by?(self) end end end using RSpec 123.should eq 123 # => true false.should eq true # => false
82. 4. Internal access control
83. module UserAdmin refine User do def purge! user.associated_records.delete_all! user.delete! end end end # in app/controllers/admin_controller.rb class AdminController < ApplicationController using UserAdmin def purge_user User.find(params[:id]).purge! end end
84. So… why is nobody using refinements?
87. “Because they’re just bad.”
88. YOU ARE EVERYTHING THAT IS WRONG WITH EVERYTHING
89. “ermm — are they? Why do you think that?”
90. “Because they’re just bad.”
91. awesome (adj.) — inspiring awe. Credit: pfala/Flickr
92. $ gem install awesome # this is not awesome
93. http://blog.honeybadger.io/benchmarking-ruby- refinements/ “TL;DR: Refinements aren’t slow. Or at least they don’t seem to be slower than ‘normal’ methods”
94. 1. Lack of understanding?
98. 2. Adding using everywhere is a giant pain in the ass?
99. 3. Rails (and Ruby) doesn't use them
100. $ fgrep 'refine ' -R rails | wc -l # => 0
101. $ fgrep 'refine ' -R ruby-2.2.3/ext | wc -l # => 0
102. 4. Implementation quirks?
103. using Shouting "hello".shout # => “HELLO" "hello".respond_to?(:shout) # => false "hello".send(:shout) # => NoMethodError ["how", "are", "you"].map(&:shout) # => NoMethodError
104. 5. Refinements solve a problem that nobody has?
105. 6. The rise of Object-Oriented Design?
106. class Shouter def initialize(string) @string = string end def shout @string.upcase + "!" end end shouted_hello = Shouter.new("hello") shouted_hello.shout # => "HELLO!"
107. I don’t know. 1. Lack of understanding 2. Adding using everywhere is a pain in the ass 3. Rails (and Ruby) doesn’t use them 4. Implementation quirks 5. They solve a problem that nobody has 6. Object-oriented design
108. I don’t know. 1. Lack of understanding 2. Adding using everywhere is a pain in the ass 3. Rails (and Ruby) doesn’t use them 4. Implementation quirks 5. They solve a problem that nobody has 6. Object-oriented design 7. Because other people have told us that they are “bad”.
109. Psssst! This isn’t a talk about refinements.
110. Sharing opinions is good
111. Blindly adopting opinions is… less good
112. Dude, globes suck.
113. Awesome! Sucks.
114. “I think you’ll find it’s a bit more complicated than that.”
115. Explore for yourselves
116. Thanks! James Adam @lazyatom lazyatom.com/refinements