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
   

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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.
   

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3. What are refinements?
   A mechanism to change the
   behaviour of an object in a
   limited and controlled way
   

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4. module Shouting
   refine String do
   def shout
   self.upcase + "!"
   end
   end
   end
   

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5. module Shouting
   refine String do
   def shout
   self.upcase + "!"
   end
   end
   end
   class Thing
   using Shouting
   "Hello".shout # => "HELLO!"
   end
   

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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
   

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7. module TexasTime
   refine Time do
   def to_s
   if hour > 12
   "Afternoon, y’all!"
   else
   super
   end
   end
   end
   end
   

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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
   

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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"
   

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10. using
    ( a developer’s guide )
    

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11. class Thing
    "hello".shout # => "HELLO!"
    end
    using Shouting
    

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12. class Thing
    "hello".shout # => "HELLO!"
    end
    using Shouting
    

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13. class Thing
    def greet
    "hello".shout
    end
    end
    Thing.new.greet # => "HELLO!"
    using Shouting
    

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14. class Thing
    def greet
    "hello".shout
    end
    end
    Thing.new.greet # => "HELLO!"
    using Shouting
    

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15. class Thing
    def greet
    "hello"
    end
    end
    Thing.new.greet
    using Shouting
    .shout # => NoMethodError
    

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16. class Thing
    using Shouting
    end
    class Thing
    "hello".shout # => NoMethodError
    end
    

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17. class Thing
    using Shouting
    class OtherThing
    "hello".shout # => "HELLO!"
    end
    end
    

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18. class Thing
    using Shouting
    class OtherThing < Thing
    "hello".shout
    end
    end
    # => NoMethodError
    

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19. class Thing
    using Shouting
    class OtherThing < Thing
    "hello".shout
    end
    end
    # => "HELLO!"
    

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20. class Thing
    using Shouting
    class OtherThing
    "hello".shout # => "HELLO!"
    end
    end
    

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21. class Thing
    using Shouting
    end
    class Thing::OtherThing
    "hello".shout # => NoMethodError
    end
    

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22. class Thing
    using Shouting
    def run
    yield
    end
    end
    Thing.new.run do
    "hello".shout
    end # => NoMethodError
    

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23. Lexical Scope
    

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24. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    

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25. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    

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26. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    

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27. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    A
    

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28. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    Parent none
    A
    Parent Top Level
    

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29. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    Parent none
    A
    Parent Top Level
    

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30. file: thing.rb
    class Thing
    using Shouting
    "hello".shout
    end
    "goodbye".shout
    Top Level
    Parent none
    A
    Parent Top Level
    

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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
    

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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
    

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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
    

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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
    

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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!”
    

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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
    

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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
    

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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
    

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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
    

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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
    

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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
    

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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
    

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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!”
    

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44. Refinements are activated in
    current and nested lexical scopes
    

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45. file: thing.rb
    class Thing
    using Shouting
    end
    class Thing
    "hello".shout
    end
    

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46. file: thing.rb
    class Thing
    using Shouting
    end
    class Thing
    "hello".shout
    end
    Top Level
    Parent none
    Refinements empty
    

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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
    

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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
    

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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
    

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50. same class ≠ same scope
    

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51. file: thing.rb
    class Thing
    using Shouting
    end
    class Other < Thing
    "hello".shout
    end
    

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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
    

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53. class hierarchy ≠ scope hierarchy
    

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54. different file = different scope
    

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55. file: thing.rb
    class Thing
    using Shouting
    def greet
    "hello".shout
    end
    end
    Thing.new.greet
    

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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
    

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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
    

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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
    

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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
    

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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
    

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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!”
    

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62. methods are evaluated using the
    lexical scope at their definition
    

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63. file: thing.rb
    class Thing
    using Shouting
    def run
    yield
    end
    end
    Thing.new.run do
    "hello".shout
    end # => NoMethodError
    

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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
    

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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
    

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66. blocks are evaluated using the
    lexical scope at their definition
    

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67. Refinements use lexical scope
    

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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”
    

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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
    

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70. Let’s use refinements!
    

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71. 1. Monkey patching
    

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72. class String
    def camelize
    self.split("_").map(&:capitalize).join
    end
    end
    "ruby_conf_2015".camelize # => "RubyConf2015"
    

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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'
    

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74. Monkey-patching Refinements
    breaks API
    expectations
    cannot affect
    distant code
    makes code harder
    to debug
    leaves lexical clue
    when active
    

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75. 2. Managing API changes
    

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76. # Ruby 1.9
    "hello".chars # => #
    # Ruby 2.0+
    "hello".chars # => ["h", "e", "l", "l", "o"]
    

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77. module OldChars
    refine String do
    def chars; each_char; end
    end
    end
    "hello".chars # => ["h", "e", "l", "l", “o"]
    using OldChars
    "hello".chars # => #
    

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78. 3. DSLs
    

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79. describe "Ruby" do
    it "should bring happiness" do
    developer = Developer.new(uses: "ruby")
    developer.should be_happy
    end
    end
    

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80. describe "Ruby" do
    it "should bring happiness" do
    developer = Developer.new(uses: "ruby")
    developer.should be_happy
    end
    end
    

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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
    

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82. 4. Internal access control
    

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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
    

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84. So… why is nobody using
    refinements?
    

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85. View Slide

86. View Slide

87. “Because they’re just bad.”
    

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88. YOU ARE EVERYTHING
    THAT IS WRONG
    WITH EVERYTHING
    

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89. “ermm — are they?
    Why do you think that?”
    

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90. “Because they’re just bad.”
    

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91. awesome (adj.) — inspiring awe.
    Credit: pfala/Flickr
    

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92. $ gem install awesome
    # this is not awesome
    

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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”
    

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94. 1. Lack of understanding?
    

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95. View Slide

96. View Slide

97. View Slide

98. 2. Adding using everywhere
    is a giant pain in the ass?
    

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99. 3. Rails (and Ruby)
    doesn't use them
    

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100. $ fgrep 'refine '
     -R rails
     | wc -l
     # => 0
     

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101. $ fgrep 'refine '
     -R ruby-2.2.3/ext
     | wc -l
     # => 0
     

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102. 4. Implementation quirks?
     

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103. using Shouting
     "hello".shout # => “HELLO"
     "hello".respond_to?(:shout) # => false
     "hello".send(:shout) # => NoMethodError
     ["how", "are", "you"].map(&:shout)
     # => NoMethodError
     

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104. 5. Refinements solve a
     problem that nobody has?
     

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105. 6. The rise of
     Object-Oriented Design?
     

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106. class Shouter
     def initialize(string)
     @string = string
     end
     def shout
     @string.upcase + "!"
     end
     end
     shouted_hello = Shouter.new("hello")
     shouted_hello.shout # => "HELLO!"
     

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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
     

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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”.
     

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109. Psssst! This isn’t a talk about
     refinements.
     

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110. Sharing opinions is good
     

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111. Blindly adopting opinions
     is… less good
     

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112. Dude, globes suck.
     

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113. Awesome!
     Sucks.
     

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114. “I think you’ll find it’s a bit more
     complicated than that.”
     

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115. Explore for yourselves
     

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116. Thanks!
     James Adam
     @lazyatom
     lazyatom.com/refinements
     

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