RedDotRubyConf

Transcript

1. Hello!
   

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2. WELCOME!
   

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3. THANK YOU!
   

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4. I bought a
   Google Glass
   

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10. I love food!
    

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11. Earth (top)
    

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12. Earth (top)
    

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13. Radius at Latitude
    R = radius of earth
    a = equatorial radius
    b = polar radius
    l = geodetic latitude
    

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14. Seattle Singapore
    Latitude 47.6097° N 1.3667° N
    Radius 6,373 km 6,357 km
    

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16. Aaron Patterson
    @tenderlove
    

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17. Ruby Core Team
    Rails Core Team
    

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18. Polymorphism
    Refactoring
    Caching
    Irresponsible Ruby
    

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19. WARNING!
    

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20. This talk is
    extremely technical
    

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21. Polymorphism
    

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22. Hide Complexity
    

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23. Decouple
    

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24. Driving a Car
    class Automatic
    def put_in_drive; end
    def gas; end
    end
    def drive(car)
    car.put_in_drive
    car.gas
    end
    car = Automatic.new
    drive(car)
    

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25. Manual Car
    class Manual
    def press_clutch; end
    def put_in_gear; end
    def release_clutch; end
    def gas; end
    end
    def drive(car)
    car.press_clutch
    car.put_in_gear
    car.release_clutch
    car.gas
    end
    car = Manual.new
    drive car
    

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26. Both Cars
    def drive(car)
    if car.is_a?(Automatic)
    car.put_in_drive
    car.gas
    else
    car.press_clutch
    car.put_in_gear
    car.release_clutch
    car.gas
    end
    end
    

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27. Polymorphic
    class Automatic
    def go
    put_in_drive
    gas
    end
    end
    class Manual
    def go
    press_clutch
    put_in_gear
    release_clutch
    gas
    end
    end
    

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28. Drive method
    def drive car
    car.go
    end
    

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29. rm Conditions
    def drive car
    if car.is_a? Automatic
    car.put_in_drive
    car.gas
    else
    car.press_clutch
    car.put_in_gear
    car.release_clutch
    car.gas
    end
    end
    

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30. Depends on Type
    def drive car
    car.go
    end
    

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31. Depends on Type
    def drive car
    car.go
    end
    

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32. Logic is removed
    from the caller
    

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33. “Caches”
    decision logic
    

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34. def drive car
    car.go
    end
    car = Automatic.new
    drive car
    “Cache”
    

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35. Refactoring
    

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36. Code is a graph
    

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37. if foo && bar
    do_something
    else
    do_something_else
    end
    Parse Tree
    

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38. Parse Tree
    if statement
    conditions positive negative
    

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39. Parse Tree:
    Structure, but no meaning
    

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40. if foo && bar
    do_something
    else
    do_something_else
    end
    Dependency Tree
    

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41. Dependency Tree
    if statement
    conditions positive negative
    foo bar
    

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42. Dependency Tree
    if statement
    conditions positive negative
    foo bar ????
    

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43. Active Support
    Callbacks API
    

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44. Callback Example
    class Hoge
    include ActiveSupport::Callbacks
    define_callbacks :save
    set_callback :save, :record
    set_callback :save, :record1
    def record; puts __method__; end
    def record1; puts __method__; end
    end
    f = Hoge.new
    f.run_callbacks :save
    

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45. Results
    $ ruby test.rb
    record
    record1
    $
    

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46. Active Record
    class Person < ActiveRecord::Base
    validates_presence_of :name
    validates_length_of :name, maximum:30
    end
    

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47. Variations
    class Foo
    include ActiveSupport::Callbacks
    define_callbacks :save
    set_callback :save, :record
    set_callback :save, -> { p "lambda1" }
    set_callback :save, ->(o) { p "lambda2" }
    set_callback :save, ->(*a) { p "lambda3" }
    set_callback :save, "puts 'hello'"
    set_callback :save, SomeClass
    end
    call method
    call lambda
    eval
    call “before”
    

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48. 6 tests!
    

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49. Variations, :if
    class Foo
    set_callback :save, :record, if: :foo
    set_callback :save, :record, if: -> { p "lambda1" }
    set_callback :save, :record, if: ->(o) { p "lambda1" }
    set_callback :save, :record, if: ->(*a) { p "lambda1" }
    set_callback :save, :record, if: "true"
    set_callback :save, :record, if: SomeClass
    end
    call method
    call lambda
    eval
    call “before”
    

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50. 6 * 6 tests!
    

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51. Variations, :unless
    class Foo
    set_callback :save, :record, unless: :foo
    set_callback :save, :record, unless: -> { p "lambda1" }
    set_callback :save, :record, unless: ->(o) { p "lambda1" }
    set_callback :save, :record, unless: ->(*a) { p "lambda1" }
    set_callback :save, :record, unless: "true"
    set_callback :save, :record, unless: SomeClass
    end
    call method
    lambda
    eval
    call “before”
    

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52. 6 * 6 * 2 tests!
    

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53. Variations, location
    class Foo
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, :after, -> { "lambda" }
    set_callback :save, :around, -> { "lambda" }
    end
    

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54. 6 * 6 * 2 * 3 tests!
    

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55. Variations, halt
    class Foo
    include ActiveSupport::Callbacks
    define_callbacks :save, terminator: "result == false"
    end
    

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56. 6 * 6 * 2 * 3 *
    tests
    

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57. Reality: 21 tests
    

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58. Callback
    Dependencies
    

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59. set_callback
    first
    

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60. set_callback
    first
    second
    third
    etc
    

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61. set_callback
    first
    second
    third
    etc
    

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62. set_callback
    first
    second
    third
    etc eval
    

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63. run_callback
    first
    second
    third
    etc
    

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64. run_callback
    first
    second
    third
    etc eval
    

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65. run_callbacks
    callbacks method
    callback method callback method
    conds callback conds callback
    

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66. Count Methods
    class Foo
    include ActiveSupport::Callbacks
    define_callbacks :save
    x = instance_methods.length
    100.times do
    set_callback :save, -> { "lambda1" }
    end
    y = instance_methods.length - x
    p NEW_METHODS: y
    end
    

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67. Run It
    $ ruby test.rb
    {:NEW_METHODS=>100}
    $
    

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68. Count Methods
    f = Foo.new
    x = Foo.instance_methods.length
    f.run_callbacks :save
    y = Foo.instance_methods.length - x
    p NEW_METHODS: y
    

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69. Run It
    $ ruby test.rb
    {:NEW_METHODS=>1}
    $
    

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70. eval based
    when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    

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71. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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72. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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73. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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74. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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75. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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76. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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77. when :before
    <<-RUBY_EVAL
    if !halted && #{@compiled_options}
    result = result = #{@source}
    halted = (#{chain.config[:terminator]})
    if halted
    halted_callback_hook(#{@raw_filter})
    end
    end
    #{code}
    RUBY_EVAL
    when :after
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    

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78. value = nil
    halted = false
    if !halted && true
    result = result = _callback_before_1
    halted = (xxx)
    if halted
    halted_callback_hook("#")
    end
    end
    if !halted && true
    result = result = _callback_before_2
    halted = (xxx)
    if halted
    halted_callback_hook("#")
    end
    end
    value = !halted && (!block_given? || yield)
    value
    class Foo
    define_callbacks :save, :terminator => 'xxx'
    set_callback :save, :before, -> { "lambda" }
    set_callback :save, -> { "lambda1" }
    end
    User Code Eval’d Code
    

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79. Currently
    ❤ Hard to understand
    ❤ Hard to change
    ❤ Memory Intensive
    ❤ Fast
    

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80. What we want
    ❤ Easy to understand
    ❤ Easy to change
    ❤ Low memory
    ❤ Fast
    

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81. ❤ Conditionals (:if, :unless)
    ❤ Callback body code
    ❤ Termination code
    Dependencies
    

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82. Leaf Nodes
    

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83. run_callbacks
    callbacks method
    callback method callback method
    conds callback conds callback
    

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84. run_callbacks
    callbacks method
    callback method callback method
    conds callback conds callback
    

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85. def _compile_filter(filter)
    case filter
    when Symbol
    filter
    when String
    "(#{filter})"
    when Proc
    method_name = "_callback_#{@kind}_#{next_id}"
    @klass.send(:define_method, method_name, &filter)
    return method_name if filter.arity <= 0
    method_name << (filter.arity == 1 ? "(self)" : " self, Proc.new ")
    else
    @klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
    def #{method_name}(&blk)
    #{method_name}_object.send(:#{method_to_call}, self, &blk)
    end
    RUBY_EVAL
    method_name
    end
    end
    Conversion Method
    

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86. compile_filter
    

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87. compile_filter
    Object
    

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88. compile_filter
    String
    

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89. compile_filter
    

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90. String contains
    ❤ A method name
    ❤ Some code to eval
    ❤ A method that changes depending on
    the arity of the proc
    

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91. We need
    CONSISTENCY
    

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92. Return a lambda!
    

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93. if object.is_a?(Symbol)
    lambda { |target,object|
    object.send target
    }
    end
    Handle Symbols
    

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94. Handle Lambdas
    if object.is_a?(Proc)
    object
    end
    

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95. Handle Objects
    if object.is_a?(Object)
    lambda { |target, object|
    object.before_filter(target)
    }
    end
    

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96. Etc...
    

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97. def make_lambda(filter)
    case filter
    when Symbol
    lambda { |target, _, &blk| target.send filter, &blk }
    when String
    l = eval "lambda { |value| #{filter} }"
    lambda { |target, value| target.instance_exec(value, &l) }
    when ::Proc
    if filter.arity > 1
    return lambda { |target, _, &block|
    raise ArgumentError unless block
    target.instance_exec(target, block, &filter)
    }
    end
    if filter.arity <= 0
    lambda { |target, _| target.instance_exec(&filter) }
    else
    lambda { |target, _| target.instance_exec(target, &filter) }
    end
    else
    lambda { |target, _, &blk|
    filter.public_send method_to_call, target, &blk
    }
    end
    end
    Conversion Method
    

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98. Move Up
    

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99. run_callbacks
    callbacks method
    callback method callback method
    conds callback conds callback
    

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100. run_callbacks
     callbacks method
     callback method callback method
     conds callback conds callback
     

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101. Conversion Method
     when :before
     <<-RUBY_EVAL
     if !halted && #{@compiled_options}
     result = result = #{@source}
     halted = (#{chain.config[:terminator]})
     if halted
     halted_callback_hook(#{@raw_filter})
     end
     end
     #{code}
     RUBY_EVAL
     when :after
     

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102. compile_method
     

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103. compile_method
     conditions,
     callback,
     next callback
     

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104. compile_method
     

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105. Return a lambda!
     

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106. if filter_type == :before
     lambda {
     halting = halted.call
     conds = conditionals.all? { |c| c.call }
     if !halting && conds
     callback_lambda.call
     end
     next_callback.call
     }
     end
     “Before” Callback
     

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107. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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108. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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109. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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110. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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111. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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112. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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113. when :before
     lambda { |env|
     target = env.target
     value = env.value
     halted = env.halted
     if !halted && user_conditions.all? { |c|
     c.call(target, value) }
     result = user_callback.call target, value
     env.halted = halted_lambda.call result
     if env.halted
     target.send :halted_callback_hook, @filter
     end
     end
     next_callback.call env
     }
     when :after
     class Foo
     define_callbacks :save, :terminator => 'xxx'
     set_callback :save, :before, -> { "lambda" }
     set_callback :save, -> { "lambda1" }
     end
     

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114. if filter_type == :after
     lambda {
     next_callback.call
     halting = halted.call
     conds = conditionals.all? { |c| c.call }
     if !halting && conds
     callback_lambda.call
     end
     }
     end
     “After” Callback
     

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115. lambda
     Linked List
     

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116. lambda lambda lambda
     Linked List
     

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117. Generate Lambda
     when :before
     # The “before” callback lambda
     when :after
     # The “after” callback lambda
     when :around
     # The “around” callback lambda
     else
     # ...
     end
     

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118. Switch lambdas
     based on type.
     (polymorphism)
     

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119. What we want
     ❤ Easy to understand
     ❤ Easy to change
     ❤ Low memory?
     ❤ Fast?
     

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120. Benchmark!
     

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121. require 'active_support/callbacks'
     class Foo
     include ActiveSupport::Callbacks
     define_callbacks :save
     100_000.times {
     set_callback :save, :before, -> { "lambda" }
     }
     end
     puts "DONE!"
     GC.start
     sleep
     

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122. Memory
     

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123. What we want
     ❤ Easy to understand
     ❤ Easy to change
     ❤ Low memory
     ❤ Fast?
     

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124. Speed
     [aaron@higgins rails (4-0-stable)]$ time bundle exec ruby rawr.rb
     DONE!
     real 0m54.925s
     user 0m53.928s
     sys 0m0.498s
     [aaron@higgins rails (4-0-stable)]$ git checkout 73aefee
     [aaron@higgins rails (73aefee...)]$ time bundle exec ruby rawr.rb
     DONE!
     real 0m17.619s
     user 0m17.385s
     sys 0m0.176s
     [aaron@higgins rails (73aefee...)]$
     

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125. Speed
     [aaron@higgins rails (4-0-stable)]$ time bundle exec ruby rawr.rb
     DONE!
     real 0m54.925s
     user 0m53.928s
     sys 0m0.498s
     [aaron@higgins rails (4-0-stable)]$ git checkout 73aefee
     [aaron@higgins rails (73aefee...)]$ time bundle exec ruby rawr.rb
     DONE!
     real 0m17.619s
     user 0m17.385s
     sys 0m0.176s
     [aaron@higgins rails (73aefee...)]$
     54s
     18s
     

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126. Runtime Speed
     class User < ActiveRecord::Base
     validates_presence_of :name
     end
     user = User.new(name: 'Aaron')
     user.valid?
     Benchmark.ips do |x|
     x.report("valid") { user.valid? }
     end
     

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127. Runtime Speed
     [aaron@higgins rails (4-0-stable)]$ bundle exec ruby test.rb
     Calculating -------------------------------------
     valid 3902 i/100ms
     -------------------------------------------------
     valid 51094.4 (±14.0%) i/s - 253630 in 5.059460s
     [aaron@higgins rails (4-0-stable)]$
     [aaron@higgins rails (73aefee...)]$ bundle exec ruby test.rb
     Calculating -------------------------------------
     valid 3726 i/100ms
     -------------------------------------------------
     valid 49397.5 (±12.1%) i/s - 245916 in 5.047747s
     [aaron@higgins rails (73aefee...)]$
     51k / s
     49k / s
     

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128. Slower. (T_T)
     

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129. More
     Polymorphism!
     

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130. lambda { |env|
     if user_conditions.all? { |c| c.call(target, value) }
     # ...
     result = user_callback.call target, value
     # ...
     end
     next_callback.call env
     }
     

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131. irb(main):001:0> [].all?
     => true
     irb(main):002:0>
     No conditions
     

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132. if user_conditions.empty?
     lambda { |env|
     # ...
     result = user_callback.call target, value
     # ...
     next_callback.call env
     }
     else
     lambda { |env|
     if user_conditions.all? { |c| c.call(target, value) }
     # ...
     result = user_callback.call target, value
     # ...
     end
     next_callback.call env
     }
     end
     

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133. Runtime Speed
     [aaron@higgins rails (4-0-stable)]$ bundle exec ruby test.rb
     Calculating -------------------------------------
     valid 3902 i/100ms
     -------------------------------------------------
     valid 51094.4 (±14.0%) i/s - 253630 in 5.059460s
     [aaron@higgins rails (4-0-stable)]$
     [aaron@higgins rails (master)]$ bundle exec ruby test.rb
     Calculating -------------------------------------
     valid 3953 i/100ms
     -------------------------------------------------
     valid 52240.9 (±10.8%) i/s - 260898 in 5.051079s
     [aaron@higgins rails (master)]$
     51k / s
     52k / s
     

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134. What we want
     ❤ Easy to understand
     ❤ Easy to change
     ❤ Low memory
     ❤ Fast
     

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135. Caching
     

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136. Active Record
     

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137. Architecture
     

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138. Person.where(...).where(...)
     

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139. AR::Relation
     AR::Relation
     AR::Base
     Person.where(...).where(...)
     Person
     .where(...)
     .where(...)
     

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140. AR::Relation
     AR::Relation
     AR::Base
     Person.where(...).where(...).to_a
     

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141. AR::Relation
     AR::Relation
     AR::Base
     Person.where(...).where(...).to_a
     Arel::Manager
     SQL AST
     WHERE
     ...
     

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142. AR::Relation
     AR::Relation
     AR::Base
     Person.where(...).where(...).to_a
     Arel::Manager
     SQL AST
     WHERE
     ...
     ...
     

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143. AR::Relation
     AR::Relation
     AR::Base
     Person.where(...).where(...).to_a
     Arel::Manager
     SQL AST
     WHERE
     ...
     ...
     FROM
     people
     SELECT
     *
     

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144. AST to SQL
     SELECT * FROM people
     WHERE ... AND ...
     

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145. AST to SQL
     SQL AST
     WHERE
     ...
     ...
     FROM
     people
     SELECT
     *
     SELECT * FROM people
     WHERE ... AND ...
     

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146. 3 Transformations
     1. Code to AR::Relation
     2. AR::Relation to SQL AST
     3. SQL AST to SQL statement
     

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147. Bind Params
     R
     ails
     >=
     3.2
     

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148. SELECT *
     FROM people
     WHERE id = ?
     

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149. Database Query
     Database
     Rails Application
     

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150. Database Query
     Database
     Rails Application
     SQL Binds
     

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151. Database Query
     Database
     Rails Application
     Records
     

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152. Database Work
     ❤ Parse SQL
     ❤ Plan Query
     ❤ Execute Query
     ❤ Return Results
     

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153. Database Work
     ❤ Parse SQL
     ❤ Plan Query
     ❤ Execute Query
     ❤ Return Results
     

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154. Query Plan
     is cached
     

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155. Parsed SQL
     is cached
     

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156. Better Caching
     

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157. Student Work
     

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158. Find Records
     Person.where(:id => 10).first
     Person.where(:id => 15).first
     Person.where(:id => 3).first
     

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159. Post.where(:id => params[:id]).first
     Generated Query Bind Parameters
     SELECT * FROM people
     WHERE id = ?
     [id, 10]
     SELECT * FROM people
     WHERE id = ?
     [id, 15]
     SELECT * FROM people
     WHERE id = ?
     [id, 3]
     

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160. Only bind
     parameters change
     

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161. class MyController
     def index
     person = Person.where(:id => params[:id]).first
     end
     end
     

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162. class MyController
     def index
     person = Person.where(:id => params[:id]).first
     end
     end
     Only dynamic value
     

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163. 1. Generate AR::Relation chain
     2. Generate SQL AST
     3. Generate SQL String
     4. Query the database
     On Every Request
     

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164. Cache Invariants
     

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165. relation = Post.where(:id => 10)
     loop do
     relation.set_binds([rand(100)])
     relation.to_a
     end
     R
     ails
     >=
     4.1
     

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166. Benchmarks
     

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167. class NoCache
     def initialize(&blk)
     @block = blk
     end
     def call(*args)
     @block.call(*args).to_a
     end
     end
     nocache = NoCache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     No Cache
     

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168. class Cache
     def initialize(&blk)
     @block = blk
     @relation = nil
     end
     def call *args
     @relation ||= @block.call(*args)
     @relation.set_binds args
     @relation.to_a
     end
     end
     nocache = Cache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     Cache
     

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169. class Cache
     def initialize(&blk)
     @block = blk
     @relation = nil
     end
     def call *args
     @relation ||= @block.call(*args)
     @relation.set_binds args
     @relation.to_a
     end
     end
     nocache = Cache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     Cache
     Cache Relation
     

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170. class Cache
     def initialize(&blk)
     @block = blk
     @relation = nil
     end
     def call *args
     @relation ||= @block.call(*args)
     @relation.set_binds args
     @relation.to_a
     end
     end
     nocache = Cache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     Cache
     Reset Binds
     

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171. Benchmark
     cache = Cache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     nocache = NoCache.new do |name, age|
     User.where(:name => name).where(:age => age)
     end
     name = names.first
     Benchmark.ips do |x|
     x.report("cache") { cache.call(name, 32) }
     x.report("nocache") { nocache.call(name, 32) }
     end
     

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172. Result
     $ bundle exec ruby qcache.rb
     Calculating -------------------------------------
     cache 456 i/100ms
     nocache 278 i/100ms
     -------------------------------------------------
     cache 4754.9 (±8.0%) i/s - 23712 in 5.018513s
     nocache 2820.4 (±5.9%) i/s - 14178 in 5.046598s
     

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173. 0
     1250
     2500
     3750
     5000
     Queries per second
     Cached Not Cached
     

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174. 1.68 times faster!
     

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175. 1. Generate AR::Relation chain
     2. Generate SQL AST
     3. Generate SQL String
     4. Query the database
     On Every Request
     Cached!
     Cached!
     

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176. Invalidation
     

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177. Record Cache
     x = Post.where(:name => ‘xxx’)
     x.to_a
     x.to_a
     x.to_a
     

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178. Invalidation
     def set_binds(list)
     @loaded = nil
     @records = []
     list.zip(values[:bind]).each do |val, bv|
     bv[1] = val
     end
     end
     

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179. Record Cache
     x = Post.where(:name => ‘xxx’)
     x.to_a
     x.set_binds(...) # cache is invalidated
     x.to_a
     x.to_a
     

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180. We can go
     even faster!
     

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181. Refactoring is the
     gateway to speed
     

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182. Use polymorphism
     

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183. Cache Invariants
     

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184. Irresponsible
     Ruby
     

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185. Ruby Values
     ❤ Immediate
     ❤ Regular
     

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186. Immediate Values
     ❤ nil
     ❤ true
     ❤ false
     ❤ Fixnum (2 ** (0.size * 8 - 2) - 1)
     

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187. 10.object_id >> 1 # => 10
     14.object_id >> 1 # => 14
     Fixnum Trick
     

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188. Regular Values
     

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189. >> o = Object.new
     => #
     >> o.object_id.to_s(16)
     => "3fd5ad9c5de8"
     >> (o.object_id << 1).to_s(16)
     => "7fab5b38bbd0"
     >>
     

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190. fiddle with memory
     

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191. Get a pointer
     require ‘fiddle’
     pointer = Fiddle::Pointer.new(offset)
     pointer[0] # => get the char * val
     pointer[0] = x # => set the val
     

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192. Fiddle with Ruby
     require ‘fiddle’
     o = Object.new
     offset = o.object_id << 1
     pointer = Fiddle::Pointer.new(offset)
     

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193. RObject Layout
     struct RObject {
     struct RBasic basic;
     union {
     struct {
     long numiv;
     VALUE *ivptr;
     struct st_table *iv_index_tbl;
     } heap;
     VALUE ary[ROBJECT_EMBED_LEN_MAX];
     } as;
     };
     

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194. RBasic
     struct RBasic {
     VALUE flags;
     const VALUE klass;
     }
     

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195. What is VALUE?
     typedef uintptr_t VALUE;
     >> require 'fiddle'
     => false
     >> Fiddle::SIZEOF_UINTPTR_T
     => 8
     

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196. Read Flags
     >> require 'fiddle'
     >> o = Object.new
     >> offset = o.object_id << 1
     >> pointer = Fiddle::Pointer.new(offset)
     >> 8.times.map { |i| pointer[i] }
     => [33, 0, 0, 0, 0, 0, 0, 0]
     >>
     

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197. Read klass
     >> 8.times.map { |i| pointer[i+8] }
     => [-64, 55, -114, -40, -88, 127, 0, 0]
     >>
     

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198. Get klass
     >> 8.times.map { |i| pointer[i+8] }
     => [-64, 55, -114, -40, -88, 127, 0, 0]
     >> addr = _.pack('C8').unpack('Q')
     => [140363164432320]
     >> Fiddle::Pointer.new(addr.first).to_value
     => Object
     >>
     

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199. Lets set the class!
     

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200. Set klass
     o = Object.new
     offset = o.object_id << 1
     pointer = Fiddle::Pointer.new(offset)
     klass_offset = String.object_id << 1
     [klass_offset].pack('Q').unpack('C8').each_with_index { |n,i|
     pointer[i + 8] = n
     }
     o.class # => String
     

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201. View Slide

202. Have Fun at
     RedDotRubyConf!
     

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203. View Slide