module Round1
  def round(i=0)
    p ' AAA '
    (self.to_f * 10**i ).to_i.to_f / (10**i)
  end
end

class Float
  def round(i=0)
    p ' BBB '
    (self.to_f * 10**i ).to_i.to_f / (10**i)
  end
  include Round1
  extend Round1
end

f = 1.111111
p f.round 1

放在 module 里为啥不打印？