gistfile1.rb

class SampleInherit
  include Comparable
  
  def <=>(anOther)
    if anOther.respond_to? 'str' and self.respond_to? 'str'
      self.str.size <=>  anOther.str.size
    elsif anOther.respond_to? 'num' and self.respond_to? 'num'
      self.num <=>  anOther.num
    elsif anOther.respond_to? 'num' and self.respond_to? 'str'
      self.str.size <=>  anOther.num
    elsif anOther.respond_to? 'str' and self.respond_to? 'num'
      self.num <=>  anOther.str.size
    end
  end 
end

class SizeMatters < SampleInherit
  attr :str

  def initialize(str)
    @str = str
  end
  
  def to_s
    @str  
  end
end

class NumMatters  < SampleInherit
  attr :num

  def initialize(num)
    @num = num
  end
  
  def to_s
    @num.to_s
  end
end


s1 = SizeMatters.new("Z")
s2 = SizeMatters.new("YY")
s3 = NumMatters.new(5)
s4 = SizeMatters.new("WWWW")
s5 = SizeMatters.new("VVVVV")
s6 = NumMatters.new(2)

puts [ s3, s6, s2, s5, s4, s1 ].sort   #=> [Z, YY, XXX, WWWW, VVVVV]