Let's Subclass Hash - What's the Worst That Could Happen?

Transcript

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5. Let’s Subclass Hash
   What’s the worst that could happen?
   

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6. My name is Michael Herold.
   Please tweet me at @mherold or
   say [email protected].
   

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8. @mherold
   

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9. This talk is about a little gem
   called …
   @mherold
   

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10. This talk is about a little gem
    called … Hashie
    @mherold
    

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11. “Hashie is a collection of classes
    and mixins that make hashes
    more powerful.”
    @mherold
    

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12. “Hashie is a collection of classes
    and mixins that make hashes
    more powerful.”
    @mherold
    

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13. @mherold
    

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14. @mherold
    @mherold
    

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15. @mherold
    @mherold
    

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16. @mherold
    

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17. –Uncle Ben
    “With great power comes
    great responsibility.”
    @mherold
    

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18. –Alexander Pope
    “To err is human …”
    @mherold
    

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19. 
    @mherold
    
    

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20. 1. Indifferent Access
    2. Mash keys
    3. Destructuring a Dash
    @mherold
    

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21. 1. Indifferent Access
    @mherold
    

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23. class MyHash < Hash
    end
    @mherold
    

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24. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    end
    @mherold
    

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25. Merge Initializer
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    dog: { name: 'Rover', sound: 'woof' }
    )
    

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26. Merge Initializer
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    dog: { name: 'Rover', sound: 'woof' }
    )
    hash[:cat] #=> "meow"
    

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27. Merge Initializer
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    dog: { name: 'Rover', sound: 'woof' }
    )
    hash[:cat] #=> "meow"
    hash[:dog] #=> {:name=>"Rover", :sound=>"woof"}
    

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28. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    end
    @mherold
    

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29. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    include Hashie::Extensions::IndifferentAccess
    end
    @mherold
    

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30. Indifferent Access
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Rover', sound: 'woof' }
    )
    

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31. Indifferent Access
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Rover', sound: 'woof' }
    )
    hash['cat'] == hash[:cat] #=> true
    

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32. Indifferent Access
    @mherold
    hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Rover', sound: 'woof' }
    )
    hash['cat'] == hash[:cat] #=> true
    hash['dog'] == hash[:dog] #=> true
    

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33. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    include Hashie::Extensions::IndifferentAccess
    end
    @mherold
    

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34. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    include Hashie::Extensions::IndifferentAccess
    end
    hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    @mherold
    

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35. class MyHash < Hash
    include Hashie::Extensions::MergeInitializer
    include Hashie::Extensions::IndifferentAccess
    end
    hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    new_dog = hash[:dog].merge(breed: 'Blue Heeler')
    #=> NoMethodError: undefined method `convert!'
    @mherold
    

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36. @mherold
    

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37. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.convert!
    end
    end
    @mherold
    

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38. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.convert!
    end
    def convert!
    # ...
    end
    end
    @mherold
    

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39. What is happening?
    @mherold
    

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40. hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    @mherold
    

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41. hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    hash.respond_to?(:convert!) #=> true
    @mherold
    

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42. hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    hash.respond_to?(:convert!) #=> true
    hash[:dog].respond_to?(:convert!) #=> true
    @mherold
    

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43. We need to go deeper.
    @mherold
    

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44. Pry + Byebug =
    @mherold
    

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45. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.convert!
    end
    end
    @mherold
    

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46. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.tap { |result| binding.pry }.convert!
    end
    end
    @mherold
    

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47. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.tap { |result| binding.pry }.convert!
    end
    end
    hash.merge(breed: 'Blue Heeler’)
    @mherold
    

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48. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.tap { |result| binding.pry }.convert!
    end
    end
    hash.merge(breed: 'Blue Heeler’)
    134: def merge(*args)
    => 135: super.tap { |result| binding.pry }.convert!
    136: end
    [1] pry(#)>
    @mherold
    

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49. @mherold
    

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50. self.class #=> Hash
    @mherold
    

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51. self.class #=> Hash
    result.class #=> Hash
    @mherold
    

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52. self.class #=> Hash
    result.class #=> Hash
    respond_to?(:convert!) #=> true
    @mherold
    

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53. self.class #=> Hash
    result.class #=> Hash
    respond_to?(:convert!) #=> true
    result.respond_to?(:convert!) #=> false
    @mherold
    

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54. self.class #=> Hash
    result.class #=> Hash
    respond_to?(:convert!) #=> true
    result.respond_to?(:convert!) #=> false
    singleton_class.ancestors
    #=> […, Hashie::Extensions::IndifferentAccess, …]
    @mherold
    

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55. self.class #=> Hash
    result.class #=> Hash
    respond_to?(:convert!) #=> true
    result.respond_to?(:convert!) #=> false
    singleton_class.ancestors
    #=> […, Hashie::Extensions::IndifferentAccess, …]
    result.singleton_class.ancestors
    #=> No indifferent access
    @mherold
    

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56. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    super.convert!
    end
    end
    @mherold
    

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57. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    - super.convert!
    end
    end
    @mherold
    

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58. module Hashie::Extensions::IndifferentAccess
    def merge(*)
    - super.convert!
    + result = super
    + IndifferentAccess.inject!(result)
    + result.convert!
    end
    end
    @mherold
    

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59. hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    @mherold
    

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60. hash = MyHash.new(
    cat: 'meow',
    'dog' => { name: 'Mango', sound: 'woof' }
    )
    new_dog = hash[:dog].merge(breed: 'Blue Heeler')
    #=> {"name"=>"Rover", "sound"=>"woof",
    "breed"=>"Blue Heeler"}
    @mherold
    

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61. Why was this a problem?
    @mherold
    

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62. Hash has 178 public methods
    @mherold
    

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65. 2. Mash keys
    @mherold
    

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66. View Slide

67. Hashie is almost synonymous
    with Mash
    @mherold
    

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70. Mash
    @mherold
    mash = Hashie::Mash.new
    mash.name? # => false
    mash.name # => nil
    mash.name = "My Mash”
    mash.name # => "My Mash"
    mash.name? # => true
    mash.inspect # =>
    

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71. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    end
    

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72. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    end
    

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73. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    case suffix
    when ‘='.freeze then assign_property(name, args.first)
    end
    end
    

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74. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    case suffix
    when ‘='.freeze then assign_property(name, args.first)
    when ‘?'.freeze then !!self[name]
    end
    end
    

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75. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    case suffix
    when ‘='.freeze then assign_property(name, args.first)
    when ‘?'.freeze then !!self[name]
    when ‘!'.freeze then initializing_reader(name)
    end
    end
    

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76. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    case suffix
    when ‘='.freeze then assign_property(name, args.first)
    when ‘?'.freeze then !!self[name]
    when ‘!'.freeze then initializing_reader(name)
    when ‘_'.freeze then underbang_reader(name)
    end
    end
    

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77. Mash
    @mherold
    def method_missing(method_name, *args, &blk)
    return self.[](method_name, &blk) if key?(method_name)
    name, suffix = method_name_and_suffix(method_name)
    case suffix
    when ‘='.freeze then assign_property(name, args.first)
    when ‘?'.freeze then !!self[name]
    when ‘!'.freeze then initializing_reader(name)
    when ‘_'.freeze then underbang_reader(name)
    else self[method_name]
    end
    end
    

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78. The README used to say “use it
    for JSON responses” …
    @mherold
    

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79. … so that’s what people do.
    @mherold
    

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80. response = HTTP.get(“http://myawesomeapi.com”)
    @mherold
    

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81. response = HTTP.get(“http://myawesomeapi.com”)
    json = JSON.parse(response.body)
    @mherold
    

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82. response = HTTP.get(“http://myawesomeapi.com”)
    json = JSON.parse(response.body)
    mash = Hashie::Mash.new(json)
    @mherold
    

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83. But remember: a Mash is a Hash
    @mherold
    

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84. Hash has 178 public methods
    @mherold
    

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85. Would any of these conflict?
    @mherold
    class
    count
    hash
    length
    trust
    zip
    

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86. mash = Hashie::Mash.new(
    name: ‘Millenium Biltmore’,
    zip: ‘90071’
    )
    @mherold
    

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87. mash = Hashie::Mash.new(
    name: ‘Millenium Biltmore’,
    zip: ‘90071’
    )
    mash.zip
    #=> [[["name", "Millenium Biltmore"]], [["zip", “90071"]]]
    @mherold
    

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88. Enumerable#zip
    @mherold
    

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89. The method is not missing
    @mherold
    

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90. … so it behaves unexpectedly.
    @mherold
    

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91. What should we do?
    @mherold
    

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92. View Slide

93. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    end
    

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94. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    

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95. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    mash = MyMash.new
    

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96. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    mash = MyMash.new
    mash.awesome = 'sauce'
    

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97. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    mash = MyMash.new
    mash.awesome = 'sauce'
    mash['awesome'] #=> ‘sauce'
    

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98. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    mash = MyMash.new
    mash.awesome = 'sauce'
    mash['awesome'] #=> 'sauce'
    mash.zip = 'a-dee-doo-dah'
    

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99. Hashie::Extension::MethodAccessWithOverride
    @mherold
    class MyMash < Hashie::Mash
    include Hashie::Extensions::MethodAccessWithOverride
    end
    mash = MyMash.new
    mash.awesome = 'sauce'
    mash['awesome'] #=> 'sauce'
    mash.zip = 'a-dee-doo-dah'
    mash.zip #=> 'a-dee-doo-dah'
    

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100. Hashie::Extension::MethodAccessWithOverride
     @mherold
     class MyMash < Hashie::Mash
     include Hashie::Extensions::MethodAccessWithOverride
     end
     mash = MyMash.new
     mash.awesome = 'sauce'
     mash['awesome'] #=> 'sauce'
     mash.zip = 'a-dee-doo-dah'
     mash.zip #=> 'a-dee-doo-dah'
     mash.__zip
     #=> [[['awesome', 'sauce'], ['zip', 'a-dee-doo-dah']]]
     

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101. 3. Destructuring a Dash
     @mherold
     

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102. View Slide

103. View Slide

104. View Slide

105. ruby = {
     name: ‘Ruby 2.5’,
     release_date: ‘Christmas’
     }
     @mherold
     

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106. ruby = {
     name: ‘Ruby 2.5’,
     release_date: ‘Christmas’
     }
     { **ruby, name: ‘Ruby 2.6’ }
     #=> {:name=>"Ruby 2.6", :release_date=>”Christmas"}
     @mherold
     

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107. Dash
     @mherold
     class PersonHash < Hashie::Dash
     end
     

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108. Dash
     @mherold
     class PersonHash < Hashie::Dash
     property :name
     property :nickname
     end
     

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109. Dash
     @mherold
     class PersonHash < Hashie::Dash
     property :name
     property :nickname
     end
     PersonHash.new(foo: ‘bar’)
     #=> NoMethodError: The property 'foo' is not defined
     

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110. @mherold
     

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111. @mherold
     sam = PersonHash.new(name: ‘Samwise’, nickname: ‘Sam’)
     

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112. @mherold
     sam = PersonHash.new(name: ‘Samwise’, nickname: ‘Sam’)
     result = { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     

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113. @mherold
     sam = PersonHash.new(name: ‘Samwise’, nickname: ‘Sam’)
     result = { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     result[:height]
     #=> NoMethodError: The property 'height' is not defined
     

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114. @mherold
     sam = PersonHash.new(name: ‘Samwise’, nickname: ‘Sam’)
     result = { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     result[:height]
     #=> NoMethodError: The property 'height' is not defined
     { height: ‘1.66m’, **sam }[:height]
     #=> “1.66m”
     

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115. @mherold
     sam = PersonHash.new(name: ‘Samwise’, nickname: ‘Sam’)
     result = { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     result[:height]
     #=> NoMethodError: The property 'height' is not defined
     { height: ‘1.66m’, **sam }[:height]
     #=> “1.66m”
     { **sam.to_h, height: ‘1.66m’ }[:height]
     #=> “1.66m”
     

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116. Why?
     @mherold
     

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117. What happens when we
     double-splat?
     @mherold
     

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118. class Test
     def to_hash
     { foo: ‘bar’ }
     end
     end
     @mherold
     

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119. class Test
     def to_hash
     { foo: ‘bar’ }
     end
     end
     { **Test.new, baz: ‘quux’ }
     => {:foo=>"bar", :baz=>”quux"}
     @mherold
     

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121. What happens when we
     double-splat inside a Hash
     literal?
     @mherold
     

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122. @mherold
     { **sam, height: ‘1.66m’ }
     

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123. @mherold
     “{ **sam, height: ‘1.66m’ }”
     

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124. @mherold
     RubyVM::InstructionSequence.compile(
     “{ **sam, height: ‘1.66m’ }”
     )
     

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125. @mherold
     RubyVM::InstructionSequence.compile(
     “{ **sam, height: ‘1.66m’ }”
     ).disasm
     

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126. @mherold
     puts RubyVM::InstructionSequence.compile(
     “{ **sam, height: ‘1.66m’ }”
     ).disasm
     

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127. @mherold
     puts RubyVM::InstructionSequence.compile(
     “{ **sam, height: ‘1.66m’ }”
     ).disasm
     == disasm: #@:1 (1,0)-(1,26)>=================
     0000 putspecialobject 1 ( 1)[Li]
     0002 putself
     0003 opt_send_without_block ,
     0006 opt_send_without_block ,
     0009 opt_send_without_block ,
     0012 putspecialobject 1
     0014 swap
     0015 putobject :height
     0017 putstring "1.66m"
     0019 opt_send_without_block ,
     0022 leave
     

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128. @mherold
     puts RubyVM::InstructionSequence.compile(
     “{ **sam, height: ‘1.66m’ }”
     ).disasm
     == disasm: #@:1 (1,0)-(1,26)>=================
     0000 putspecialobject 1 ( 1)[Li]
     0002 putself
     0003 opt_send_without_block ,
     0006 opt_send_without_block ,
     0009 opt_send_without_block ,
     0012 putspecialobject 1
     0014 swap
     0015 putobject :height
     0017 putstring "1.66m"
     0019 opt_send_without_block ,
     0022 leave
     

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129. Look for core_hash_merge_kwd
     in Ruby’s source code
     @mherold
     

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130. @mherold
     static VALUE
     core_hash_merge_kwd(int argc, VALUE *argv)
     {
     VALUE hash, kw;
     rb_check_arity(argc, 1, 2);
     hash = argv[0];
     kw = rb_to_hash_type(argv[argc-1]);
     if (argc < 2) hash = kw;
     rb_hash_foreach(kw, argc < 2 ? kwcheck_i : kwmerge_i, hash);
     return hash;
     }
     

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131. @mherold
     static VALUE
     core_hash_merge_kwd(int argc, VALUE *argv)
     {
     VALUE hash, kw;
     rb_check_arity(argc, 1, 2);
     hash = argv[0];
     kw = rb_to_hash_type(argv[argc-1]);
     if (argc < 2) hash = kw;
     rb_hash_foreach(kw, argc < 2 ? kwcheck_i : kwmerge_i, hash);
     return hash;
     }
     

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132. Ruby’s VM casts the value to a
     hash …
     @mherold
     

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133. … but only when it isn’t already a
     Hash.
     @mherold
     

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134. Recall: a Dash is a Hash.
     @mherold
     

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135. The VM does not call #to_hash
     @mherold
     

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136. @mherold
     { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     

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137. @mherold
     { **sam, height: ‘1.66m’ }
     #=> {:name=>"Samwise", :nickname=>"Sam", :height=>"1.66m"}
     sam.merge(height: ‘1.66m’)
     #=> NoMethodError: The property 'height' is not defined
     

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138. @mherold
     

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139. @mherold
     static VALUE
     core_hash_merge_kwd(int argc, VALUE *argv)
     {
     VALUE hash, kw;
     rb_check_arity(argc, 1, 2);
     hash = argv[0];
     kw = rb_to_hash_type(argv[argc-1]);
     if (argc < 2) hash = kw;
     rb_hash_foreach(kw, argc < 2 ? kwcheck_i : kwmerge_i, hash);
     return hash;
     }
     

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140. The VM does not call #merge
     @mherold
     

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141. Dash’s property logic exists in
     Ruby so it isn’t run.
     @mherold
     

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142. Unfortunately, we can’t “fix” this.
     @mherold
     

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143. So we wrote it up in the
     README.
     @mherold
     

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144. 
     @mherold
     

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145. @mherold
     

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146. 1. Indifferent Access
     2. Mash keys
     3. Destructuring a Dash
     @mherold
     

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147. class MyHash < Hash
     @mherold
     

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148. Your interface is suddenly 173
     methods (and counting)
     @mherold
     

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149. Do you think you can catch all
     the corner cases?
     @mherold
     

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150. (If so, please contact me - we’d
     love another co-maintainer! )
     @mherold
     

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151. But wait …
     

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152. A wild PSA appears!
     

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153. Hashie::Mash
     @mherold
     

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154. 
     @mherold
     

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155. View Slide

156. View Slide

157. Gem Name Total Downloads Rank
     omniauth 199
     inspec 262
     elasticsearch-api 264
     elasticsearch-transport 265
     restforce 567
     chef-zero 716
     elasticsearch-model 782
     ridley 890
     zendesk_api 911
     Data from the 2018-11-12 RubyGems.org data dump
     Queries can be found at https://michaeljherold.com/rubyconf2018
     @mherold
     

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158. 
     @mherold
     

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159. You might not need Hashie::Mash
     @mherold
     

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160. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     @mherold
     

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161. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = Hashie::Mash.new(json, object_class: OpenStruct)
     #=> # foo="bar">
     @mherold
     

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162. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = Hashie::Mash.new(json, object_class: OpenStruct)
     #=> # foo="bar">
     parsed.foo #=> "bar"
     @mherold
     

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163. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = Hashie::Mash.new(json, object_class: OpenStruct)
     #=> # foo="bar">
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     @mherold
     

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164. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = Hashie::Mash.new(json, object_class: OpenStruct)
     #=> # foo="bar">
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     parsed[:foo] #=> "bar"
     @mherold
     

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165. json = JSON.parse(<{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = Hashie::Mash.new(json, object_class: OpenStruct)
     #=> # foo="bar">
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     parsed[:foo] #=> "bar"
     parsed.bazes #=> ["baz", “quux"]
     @mherold
     

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166. Hashie::Mash
     @mherold
     

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167. 
     @mherold
     

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168. require ‘json’
     require ‘ostruct’
     @mherold
     

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169. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     @mherold
     

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170. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = JSON.parse(json, object_class: OpenStruct)
     #=> #
     @mherold
     

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171. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = JSON.parse(json, object_class: OpenStruct)
     #=> #
     parsed.foo #=> "bar"
     @mherold
     

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172. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = JSON.parse(json, object_class: OpenStruct)
     #=> #
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     @mherold
     

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173. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = JSON.parse(json, object_class: OpenStruct)
     #=> #
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     parsed[:foo] #=> "bar"
     @mherold
     

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174. json = <{
     "foo": "bar",
     "bazes": [
     "baz",
     "quux"
     ]
     }
     JSON
     parsed = JSON.parse(json, object_class: OpenStruct)
     #=> #
     parsed.foo #=> "bar"
     parsed['foo'] #=> "bar"
     parsed[:foo] #=> "bar"
     parsed.bazes #=> ["baz", “quux"]
     @mherold
     

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175. 
     @mherold
     

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176. My name is Michael Herold.
     Please tweet me at @mherold or
     say [email protected].
     

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177. View Slide