Kyosuke MOROHASHI

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1 Practical Meta Programming on Rails Ruby 1 in MOROHASHI Kyosuke

2 Kyosuke MOROHASHI

5 Aga toolbox

7 Ruby " " Ruby

9 Ruby " " Ruby

11 Ruby

12 Ruby

14 class Book def def = title

15 class Book def def = title

16 'title'?

17 class Book attr_accessor :title

18 def attr_accessor(name) define_method(name) do define_method("#{name}=") do val val)

19 define_method(:title) do define_method("title=") do val val)

20 define_method(:title) do define_method("title=") do val val)

21 define_method(:title) do define_method("title=") do val val)

23 Ruby

24 toolbox

25 (reflection) _( )

27 Class.is_a?(Object) #=> true Ruby Module Class

28 klasses = { 'array klass' => Array, 'hash klass' => Hash, } def class_name(klass) klass.name klasses['array klass'].new #=> [] class_name(klasses['hash klass']) #=> "Hash"

29 Class.is_a?(Object) #=> true include ext define_method Module

30 (Proc) Ruby

31 (Proc) # イテレータや処理の差し替え multiplier = ->(i) { i * 2 } square = ->(i) { i ** 2 } [1, 2, 3].map(&multiplier) [1, 2, 3].map(&square) # リソースの開閉 File.open(path, 'w') { f f.puts('content') } # 遅延評価 scope :fresh, -> { where('created_at >?', 3.hour.ago) }

32 You must unlearn what you have learned.

33 Object#s

34 Object#s def up_or_down(condition) up_or_down = condition? :upcase? :downcase 'Ruby'.s(up_or_down) up_or_down(true) # => 'RUBY' up_or_down(false) # => 'ruby'

35 define_method def

36 define_method class Foo foo = 'FOO' define_method(:foo1) do puts foo + '1' def foo2 puts foo + '2' obj = Foo.new obj.foo1 #=> 'FOO1' obj.foo2 #=> NameError

37 class_eval/ instance_eval Ruby

38 class_eval/ instance_eval class_eval (module_eval) Class private Class instance_eval private

39 class Foo def = message Foo.class_eval %q[ def greet "#{@message} you!" ] foo = Foo.new('hi') p foo.greet #=> 'hi you!' p foo.instance_eval } #=> 'hi'

40 instance_variable_set/ instance_variable_get class_varaible_set/ get

41 class Foo def = message foo = Foo.new('hi') foo.instance_variable_get('@message') #=> 'hi'

42 method_missing!! ActiveRecord

43 method_missing!! class Foo def method_missing(method, *args, &block) if method = :hi 'hello' else super Foo.new.hi #=> 'hello'

44 include,ext mixin include ext ( )

45 included, exted include ext inherited

46 included, exted module MyModule def self.included(base) "included by #{base}" def self.exted(obj) "exted by #{obj}" class MyClass include MyModule # => "included by MyClass" MyClass.new.ext(MyModule) # => "exted by #<MyClass:0x007fd

47 ActiveSupport::Concern Rails include ClassMethods ext included {} included

48 ActiveSupport::Concern module MyModule included(base) "included by #{base}" module ClassMethods def hi; 'hello' ; class MyClass include MyModule # => "included by MyClass" MyClass.hi # => "hello"

49 Ruby Ruby

52 Book = Class.new do define_method(:initialize) do attrs attrs.each do key, value if respond_to?("#{key}=") s("#{key}=", value) else instance_variable_set("@#{key}", value) define_method(:price=) do price_str instance_variable_set( '@price', price_str.delete(',').to_i ) p Book.new(author: 'moro', price: '1,980')

53 class Book def = attrs[:author] self.price = attrs[:price] def = Integer(price_str.delete(',')) Book.new(author: 'moro', price: '1,980')

54 " " s, eval

56 ActiveRecord::Base.has_many assoc_name assoc_name で指定された複数の子レコードへの関連を定義する

57 class Books < ActiveRecord::Base has_many :reviews Book#reviews #reviews= #review_ids #review_ids=... Book#reviews.build reviews.create reviews.each { review... } reviews.where(...)

58 def has_many(name, opts = {}) class_eval <<-RUBY def #{name} klass = #{name.to_s.classify} klass.where(#{fk}: id) def #{name}=(value) values.each do value #{name.to_s.classify}.create!(...) RUBY

59 ActiveRecord::Base.has_many assoc_name assoc_name で指定された複数の子レコードへの関連を扱うオブジェクトのためのラッパーメソッドを定義する

60 Book#reviews

61 def define_readers mixin.class_eval <<-CODE, FILE, LINE + def #{name}(*args) association(:#{name}).reader(*args) CODE

62 Association owner target owner id target fk scope target

63 = Active Record Associations This is the root class of all associations ('+ Foo' signifies an included module Foo): Association SingularAssociation HasOneAssociation HasOneThroughAssociation + ThroughAssociation BelongsToAssociation BelongsToPolymorphicAssociation CollectionAssociation HasAndBelongsToManyAssociation HasManyAssociation HasManyThroughAssociation + ThroughAssociation

65 def define_readers mixin.class_eval <<-CODE, FILE, LINE + def #{name}(*args) association(:#{name}).reader(*args) CODE

69 (Post) (Comment) (Photo) Post URL

70 class Post < AR::Base after_save :submit_content_monitoring private def submit_content_monitoring content = [title, body].join("\n\n") url = Rails.config.censoring_point req = Net:: req.set_form_data('content' => content) Net::HTTP.start(url.hostname, url.port) do htt http.request(req)

71 class Comment < AR::Base... def submit_content_monitoring content = body... class Photo < AR::Base... def submit_content_monitoring content = "<img src=' />"...

73 class Post < AR::Base after_save :submit_content_monitoring private def submit_content_monitoring content = [title, body].join("\n\n") url = Rails.config.censoring_point req = Net:: req.set_form_data('content' => content) Net::HTTP.start(url.hostname, url.port) do htt http.request(req)

74 class Post < AR::Base after_save :submit_content_monitoring private def submit_content_monitoring Censoring.new( [title, body].join("\n\n"), Rails.config.censoring_point ).submit

75 class Censoring def initialize(content, = = url def submit req = Net:: req.set_form_data('content' do h http.request(req)

76 class Post < AR::Base after_save :submit_content_monitoring private def submit_content_monitoring Censoring.new( [title, body].join("\n\n"), Rails.config.censoring_point ).submit

78 class CensorAdapter def initialize(point, = = block def submit(record) content # post_adapter = CensorAdapter.new(point) do post [post.title, post.body].join("\n\n") post_adapter.submit(post)

79 class Post < AR::Base = CensorAdapter.new(config.point) do post [post.title, post.body].join("\n\n") after_save :submit_content_monitoring private def

80 class Comment < AR::Base = CensorAdapter.new(config.point) do comment comment.body after_save :submit_content_monitoring private def

81 class Photo < AR::Base = CensorAdapter.new(config.point) do photo "<img src=' />" after_save :submit_content_monitoring private def

83 module CeonsoringDsl def censor_content(url, &block) adapter = CensorAdapter.new(url, block) after_save { record adapter.submit(record) }

84 class Post < AR::Base ext CensoringDsl censor_content(config.point) do post [post.title, post.body].join("\n\n")

86 module Censorable ext ActiveSupport::Concern module ClassMethods def censor_content(url, &block) adapter = Censorable::Adapter.new(url, block after_save { record adapter.submit(record) class Adapter... class Request...

87 class Post < ActiveRecord::Base include Censorable censor_content(config.censoring_point) do pos [post.title, post.body].join("\n\n")

89 Censorable::Request Censorable::Adapter AR(AMo)

90 Censorable::Request #initialize(content, url) 送信内容とエンドポイントを受け取り #submit そこに POST する #submit

91 Censorable::Adapter #initialize(url, &block) エンドポイントとデータ変換方法 (Proc) を受け取り #submit(record) 初期化時の url と record から作った送信内容で Request を作り submit() &block record

92 AR(AMo) #create! 保存されるデータから適切に作られた内容が監視サービスに送信される

96 Ruby " " Ruby

99 ( " " )

100

101

102 Matz says: Ruby Ruby Ruby Ruby Ruby

Presentation

Presentation メタプログラミング Ruby LLPlanets 2011-8-20 征典 kdmsnr@gmail.com 1/50 征典 -kdmsnr 2/50 MF'sbliki 3/50 Ruby におけるメタプログラミングとは? 4/50 内部 DSL を書くことである 5/50 プログラミング語 Ruby 8 章リフレクションとメタプログラミング豊富なリフレクション APIを使いメタプログラミングを実現する