[Ruby] ancestorsが返すもの

RubyのバージョンごとにObject、Class、Arrayのancestorsを確認してみる。

1.8.7

$ ruby -e "p Class.ancestors"
# => [Class, Module, Object, Kernel]
$ ruby -e "p Object.ancestors"
# => [Object, Kernel]
$ ruby -e "p Array.ancestors"
# => [Array, Enumerable, Object, Kernel]

1.9.2

$ ruby -e "p Class.ancestors"
# => [Class, Module, Object, Kernel, BasicObject]
$ ruby -e "p Object.ancestors"
# => [Object, Kernel, BasicObject]
$ ruby -e "p Array.ancestors"
# => [Array, Enumerable, Object, Kernel, BasicObject]

1.9.3

$ ruby -e "p Class.ancestors"
# => [Class, Module, Object, Kernel, BasicObject]
$ ruby -e "p Object.ancestors"
# => [Object, Kernel, BasicObject]
$ ruby -e "p Array.ancestors"
# => [Array, Enumerable, Object, Kernel, BasicObject]

2.0.0

$ ruby -e "p Class.ancestors"
# => [Class, Module, Object, Kernel, BasicObject]
$ ruby -e "p Object.ancestors"
# => [Object, Kernel, BasicObject]
$ ruby -e "p Array.ancestors"
# => [Array, Enumerable, Object, Kernel, BasicObject]

1.9.2のときにBasicObjectが追加されて以降は変更はないようだ。