UFO

class Hoge
  include Comparable
  attr_accessor :age

  def initialize(age)
    @age = age
  end

  def <=>(other)
    self.age <=> other.age
  end
end

list = [Hoge.new(20), Hoge.new(10), Hoge.new(15)]

list.sort.each do |v|
  puts v.age
end

ありがとうございます。