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Rubyのnilってなんじゃ

Ruby

Posted at 2015-09-30

なんか怖かったのでメモ。

>> nil.class
=> NilClass
>> nil.class.superclass
=> Object
>> nil.class.superclass.superclass
=> BasicObject
>> nil.class.superclass.superclass.superclass
=> nil
>> nil.class.superclass.superclass.superclass.superclass
NoMethodError: undefined method `superclass' for nil:NilClass
        from (irb):11
        from /usr/local/rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'

この入れ子構造はもちろん、

>> nil.class.superclass.superclass.superclass.class
=> NilClass
>> nil.class.superclass.superclass.superclass.class.superclass
=> Object
>> nil.class.superclass.superclass.superclass.class.superclass.superclass
=> BasicObject
>> nil.class.superclass.superclass.superclass.class.superclass.superclass.class
=> Class

となる。

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