感觉这个有点新意。

def data_class(fields)
  names = fields.keys
  pattern = fields.values.join

  Class.new do
    attr_reader :values

    define_method :initialize do |byte_string|
      @values = byte_string.unpack(pattern)
    end

    names.each_with_index do |name, i|
      define_method name do
        values[i]
      end
    end
  end

end

RGBColorData = data_class(red: "C", green: "C", blue: "C")

binary = [255, 128, 192].pack("CCC")
color = RGBColorData.new(binary)
color.red   #=> 255
color.green #=> 128
color.blue  #=> 192

http://monkeyandcrow.com/blog/building_classes_dynamically/