ActiveSupport::Concern で学ぶRuby

11/22のEbisu.rbでLTをした際の資料です。
ActiveSupport::Concernがどう実現されているかを実際にコードを読んで学び、Rubyへの理解を深めることを目的とした内容です。

Transcript

1. "DUJWF4VQQPSU$PODFSO
 ͰֶͿ3VCZ &CJTVSC
   
   
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   ࿨ਅʢ!LB[VNBYʣ
   w ܦྺ
   w ɹ
   ΧΧΫίϜೖࣾ
   w ʙ
   ৯΂ϩά
   w ʙ
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   w झຯ
   w ཱྀ
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3. wʮ฻Β͠Λૉఢʹஸೡʹɻʯ ΛςʔϚʹͨ͠ϥΠϑελΠϧ ϝσΟΞɺ&$Ϟʔϧ
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   w୅ޙ൒ʙ୅ঁੑ͕ϝΠϯ λʔήοτ
4. ࠓ೔ͷΰʔϧ w "DUJWF4VQQPSU$PODFSOͷίʔυΛಡΉ͜ͱΛ௨ͯ͠ 3VCZ΁ͷཧղΛਂΊΔ
   w ର৅ɿ3VCZॳதڃऀ
5. "DUJWF4VQQPSU$PODFSOͱ͸ w 3BJMTͷ"DUJWF4VQQPSUϥΠϒϥϦͷϞδϡʔϧͷͭ
   w ϞδϡʔϧΛJODMVEF͢Δࡍʹগͳ͍هड़ͰΠϯελϯε ϝιουͱΫϥεϝιουΛ௥Ճͯ͘͠ΕΔ
   w JODMVEF͢ΔϞδϡʔϧͷґଘؔ܎Λ؅ཧͯ͘͠ΕΔ
6. ෮श
7. 0CKFDUFYUFOE w ࢦఆͨ͠ϞδϡʔϧͷΠϯελϯεϝιουΛ
   TFMG
   ͷಛ ҟϝιουͱͯ͠௥Ճ͢Δ module M def my_method 'Ebisu.rb' end end class C1 include M end class C2 extend M end C1.new.my_method #=> "Ebisu.rb" C2.my_method #=> "Ebisu.rb"
8. "DUJWF4VQQPSU$PODFSOͷྫᶃ module M def self.included(base) base.extend ClassMethods base.class_eval do scope :disabled, ->{ where(disabled: true) } end end module ClassMethods ... end end module M extend ActiveSupport::Concern included do scope :disabled, ->{ where(disabled: true) } end class_methods do ... end end $PODFSOͳ͠ $PODFSO͋Γ w Ϋϥεϝιουͷ௥Ճ΍JODMVEFͨ͠ଆͷΫϥεϝιουͷݺͼग़͠Λ؆ ୯ʹॻ͚Δ
9. "DUJWF4VQQPSU$PODFSOͷྫᶄ module M1 def self.included(base) base.extend(ClassMethods) end module ClassMethods def m1_class_method 'M1!' end end end module M2 include M1 def self.included(base) base.extend(ClassMethods) end module ClassMethods def m2_class_method m1_class_method + ' M2!' end end end class C include M2 end C.m2_class_method #=> NameError: undefined local variable or method `m1_class_method' for C:Class $PODFSOͳ͠ w JODMVEF͢ΔϞδϡʔϧͷґଘؔ܎Λ؅ཧͯ͘͠ΕΔ module M1 extend ActiveSupport::Concern class_methods do def m1_class_method 'M1!' end end end module M2 extend ActiveSupport::Concern include M1 class_methods do def m2_class_method m1_class_method + ' M2!' end end end class C include M2 end C.m2_class_method #=> "M1! M2!" $PODFSO͋Γ
10. Ͱ͸ɺૣ଎ "DUJWF4VQQPSU$PODFSOͷ ίʔυΛಡΜͰΈ·͠ΐ͏
11. 1 module ActiveSupport 2 module Concern 3 class MultipleIncludedBlocks < StandardError #:nodoc: 4 def initialize 5 super "Cannot define multiple 'included' blocks for a Concern" 6 end 7 end 8 9 def self.extended(base) #:nodoc: 10 base.instance_variable_set(:@_dependencies, []) 11 end 12 13 def append_features(base) 14 if base.instance_variable_defined?(:@_dependencies) 15 base.instance_variable_get(:@_dependencies) << self 16 return false 17 else 18 return false if base < self 19 @_dependencies.each { |dep| base.include(dep) } 20 super 21 base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods) 22 base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block) 23 end 24 end 25 26 def included(base = nil, &block) 27 if base.nil? 28 raise MultipleIncludedBlocks if instance_variable_defined?(:@_included_block) 29 30 @_included_block = block 31 else 32 super 33 end 34 end 35 36 def class_methods(&class_methods_module_definition) 37 mod = const_defined?(:ClassMethods, false) ? 38 const_get(:ClassMethods) : 39 const_set(:ClassMethods, Module.new) 40 41 mod.module_eval(&class_methods_module_definition) 42 end 43 end 44 end
12. ͨͬͨߦʂ
    ۭߦൈ͘ͱߦʂ
13. 1 module ActiveSupport 2 module Concern 3 class MultipleIncludedBlocks < StandardError #:nodoc: 4 def initialize 5 super "Cannot define multiple 'included' blocks for a Concern" 6 end 7 end 8 9 def self.extended(base) #:nodoc: 10 base.instance_variable_set(:@_dependencies, []) 11 end 12 13 def append_features(base) 14 if base.instance_variable_defined?(:@_dependencies) 15 base.instance_variable_get(:@_dependencies) << self 16 return false 17 else 18 return false if base < self 19 @_dependencies.each { |dep| base.include(dep) } 20 super 21 base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods) 22 base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block) 23 end 24 end 25 26 def included(base = nil, &block) 27 if base.nil? 28 raise MultipleIncludedBlocks if instance_variable_defined?(:@_included_block) 29 30 @_included_block = block 31 else 32 super 33 end 34 end 35 36 def class_methods(&class_methods_module_definition) 37 mod = const_defined?(:ClassMethods, false) ? 38 const_get(:ClassMethods) : 39 const_set(:ClassMethods, Module.new) 40 41 mod.module_eval(&class_methods_module_definition) 42 end 43 end 44 end
14. $PODFSOͷίʔυΛಡΉᶃ  Ϟδϡʔϧ͕"DUJWF4VQQPSU$PODFSOΛFYUFOE͢Δͱ TFMGFYUFOEFE͕ݺͼग़͞ΕΔ
     FYUFOE͞ΕͨϞδϡʔϧʹ!@EFQFOEFODJFTΛఆٛ͠ɺۭ഑ྻ Λ୅ೖ͢Δ
    ˞͜ΕҎ߱"DUJWF4VQQPSU$PODFSO͕FYUFOE͞ΕͨϞδϡʔϧͷ͜ͱΛDPODFSOͱදه͠·͢ def self.extended(base) #:nodoc: base.instance_variable_set(:@_dependencies, []) end
15. 1 module ActiveSupport 2 module Concern 3 class MultipleIncludedBlocks < StandardError #:nodoc: 4 def initialize 5 super "Cannot define multiple 'included' blocks for a Concern" 6 end 7 end 8 9 def self.extended(base) #:nodoc: 10 base.instance_variable_set(:@_dependencies, []) 11 end 12 13 def append_features(base) 14 if base.instance_variable_defined?(:@_dependencies) 15 base.instance_variable_get(:@_dependencies) << self 16 return false 17 else 18 return false if base < self 19 @_dependencies.each { |dep| base.include(dep) } 20 super 21 base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods) 22 base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block) 23 end 24 end 25 26 def included(base = nil, &block) 27 if base.nil? 28 raise MultipleIncludedBlocks if instance_variable_defined?(:@_included_block) 29 30 @_included_block = block 31 else 32 super 33 end 34 end 35 36 def class_methods(&class_methods_module_definition) 37 mod = const_defined?(:ClassMethods, false) ? 38 const_get(:ClassMethods) : 39 const_set(:ClassMethods, Module.new) 40 41 mod.module_eval(&class_methods_module_definition) 42 end 43 end 44 end
16. .PEVMFBQQFOE@GFBUVSFT w .PEVMFJODMVEFͷ࣮ମ
    w JODMVEF͞ΕͨϞδϡʔϧ͕ܧঝνΣʔϯʹؚ·Ε͍ͯͳ͚Ε͹ܧ ঝνΣʔϯʹϞδϡʔϧΛ௥Ճ͢Δ
    w ΦʔόʔϥΠυ͢ΔͱϞδϡʔϧ͕JODMVEF͞Εͳ͘ͳΔ module M def self.append_features end end class C include M end C.ancestors #=> [C, Object, Kernel, BasicObject]
17. $PODFSOͷίʔυΛಡΉᶄ  !@EFQFOEFODJFT͕ఆٛ͞Ε͍ͯΕ͹ʢ
    DPODFSOͰ͋Ε͹ʣɺ !@EFQFOEFODJFTʹࣗ෼ࣗ਎Λ௥Ճͯ͠GBMTFΛฦ͢
    
    JODMVEF͠ͳ͍
     DPODFSOͰͳ͍৔߹ɺܧঝνΣʔϯʹࣗ෼ࣗ਎͕௥Ճ͞Ε͍ͯͳ͚Ε͹ɺґଘ ͨ͠DPODFSOΛ࠶ؼతʹJODMVEF͍͖ͯ͠ɺ࠷ޙʹTVQFSͰܧঝνΣʔϯʹࣗ ෼ࣗ਎Λ௥Ճ͢Δ
     $MBTT.FUIPETϞδϡʔϧΛFYUFOE͢Δ
     JODMVEFEʹ౉ͨ͠ϒϩοΫΛJODMVEFͨ͠ଆͷΫϥεͷίϯςΩετͰ࣮ߦ͢Δ def append_features(base) if base.instance_variable_defined?(:@_dependencies) base.instance_variable_get(:@_dependencies) << self return false else return false if base < self @_dependencies.each { |dep| base.include(dep) } super base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods) base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block) end end
18. 1 module ActiveSupport 2 module Concern 3 class MultipleIncludedBlocks < StandardError #:nodoc: 4 def initialize 5 super "Cannot define multiple 'included' blocks for a Concern" 6 end 7 end 8 9 def self.extended(base) #:nodoc: 10 base.instance_variable_set(:@_dependencies, []) 11 end 12 13 def append_features(base) 14 if base.instance_variable_defined?(:@_dependencies) 15 base.instance_variable_get(:@_dependencies) << self 16 return false 17 else 18 return false if base < self 19 @_dependencies.each { |dep| base.include(dep) } 20 super 21 base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods) 22 base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block) 23 end 24 end 25 26 def included(base = nil, &block) 27 if base.nil? 28 raise MultipleIncludedBlocks if instance_variable_defined?(:@_included_block) 29 30 @_included_block = block 31 else 32 super 33 end 34 end 35 36 def class_methods(&class_methods_module_definition) 37 mod = const_defined?(:ClassMethods, false) ? 38 const_get(:ClassMethods) : 39 const_set(:ClassMethods, Module.new) 40 41 mod.module_eval(&class_methods_module_definition) 42 end 43 end 44 end
19. म০ w ϝιουͷ࠷ޙʹ෇͖ͷҾ਺Λ௥Ճ͢Δ͜ͱͰɺϝιουʹϒϩο ΫΛ౉͢͜ͱ͕Ͱ͖Δ
    w Λ෇͚ͨ··ͩͱϒϩοΫͱͯ͠ɺΛ෇͚ͳ͍ͱ1SPDͱͯ͠࢖ ͑Δ def my_method(&hoge) hoge end a = my_method {|name| "Hello, #{name}!" } a.class #=> Proc a.call("Ebisu.rb") #=> "Hello, Ebisu.rb!"
20. $PODFSOͷίʔυΛಡΉᶅ !@JODMVEFE@CMPDL
    ʹ
    JODMVEFE
    ʹ౉͞ΕͨϒϩοΫͷ1SPDΦϒ δΣΫτΛ୅ೖ͢Δ def included(base = nil, &block) if base.nil? raise MultipleIncludedBlocks if instance_variable_defined?(:@_included_block) @_included_block = block else super end end def class_methods(&class_methods_module_definition) mod = const_defined?(:ClassMethods, false) ? const_get(:ClassMethods) : const_set(:ClassMethods, Module.new) mod.module_eval(&class_methods_module_definition) end $MBTT.FUIPETϞδϡʔϧʹ
    DMBTT@NFUIPET
    ʹ౉͞ΕͨϒϩοΫͷ ಺༰Λ௥Ճ͢Δ
21. Ҏ্ʂ
22. ·ͱΊ w "DUJWF4VQQPSU$PODFSO͕Ͳ͏࣮ݱ͞Ε͍ͯΔ͔Λ࣮ࡍ ʹίʔυΛಡΜͰֶͼɺ3VCZ΁ͷཧղΛਂΊͨ
    w 3BJMTΛ࢖͍ͬͯͯ͜ΕͬͯͲ͏΍࣮ͬͯݱͯ͠ΔΜͩΖ ͏ͱࢥͬͨΒɺ3BJMTͷίʔυΛಡΜͰΈΔͱ͍ΖΜͳൃ ݟ͕͋Δ