to_s

何がsuperなのか

irb(main):001* module A
irb(main):002*   def to_s
irb(main):003*     "<A> #{super}"
irb(main):004*   end
irb(main):005> end
=> :to_s
irb(main):006* module B
irb(main):007*   def to_s
irb(main):008*     "<B> #{super}"
irb(main):009*   end
irb(main):010> end
=> :to_s
irb(main):011* class Product
irb(main):012*   prepend A
irb(main):013*   prepend B
irb(main):014*   def to_s
irb(main):015*     "<Product> #{super}"
irb(main):016*   end
irb(main):017> end
=> :to_s
irb(main):018> product = Product.new
=> #<Product:0x000000010cbc7d68>
irb(main):019> product.to_s
=> "<B> <A> <Product> #<Product:0x000000010cbc7d68>"

メソッド名も色々変更してみた

irb(main):002* module A
irb(main):003*   def hihi
irb(main):004*     "#{super}"
irb(main):005*   end
irb(main):006> end
=> :hihi
irb(main):007* class B
irb(main):008*   include A
irb(main):009*   def hihi
irb(main):010*     "#{super} #{super}"
irb(main):011*   end
irb(main):012> end
=> :hihi
irb(main):013> b = B.new
=> #<B:0x0000000104f5ec68>
irb(main):014> b.hihi
(irb):4:in `hihi': super: no superclass method `hihi' for #<B:0x0000000104f5ec68> (NoMethodError)

no superclass method

super [bug]
Kernelのメソッド内でsuperを呼んだ時に、存在しないsuperclass にアクセスしようとするバグの修正。

module Kernel def foo super end end

foo

# => ruby 1.8.3 (2005-09-21) [i686-linux] -:3:in foo': method foo' called on terminated object (0xb7e06970) (NotImplementedError) from -:7 # => ruby 1.8.4 (2005-12-22) [i686-linux] -:3:in foo'-:3: warning: too many arguments for format string : super: no superclass method foo' (NoMethodError) from -:7

irb(main):001* module A
irb(main):002*   def to_s
irb(main):003*     "#{super}"
irb(main):004*   end
irb(main):005> end
=> :to_s
irb(main):006* class B
irb(main):007*   include A
irb(main):008*   def to_s
irb(main):009*     "#{super} #{super}"
irb(main):010*   end
irb(main):011> end
=> :to_s
irb(main):012> b = B.new
=> #<B:0x000000011029f750>
irb(main):013> b.to_s
=> "#<B:0x000000011029f750> #<B:0x000000011029f750>"

to_sとは？

to_s -> String
オブジェクトの文字列表現を返します。