class.inherited

こんな機能あったのか

irb(main):007:0> class M
irb(main):008:1>  def self.inherited(subclass)
irb(main):009:2>    p "inherited by #{subclass}"
irb(main):010:2>  end
irb(main):011:1> end
=> nil
irb(main):012:0> class B < M
irb(main):013:1> end
"inherited by B"
=> nil

ふーん。何に使うんだろうか・・・
ちなみにリファレンスにも書いてあったけど、

irb(main):046:0> class F < M
irb(main):047:1>   puts "i'm F and i'm born now"
irb(main):048:1> end
"inhereted by F"
i'm F and i'm born now
=> nil

順序はこうなのね。