Object relationship between Device, Data, and Format

In the world of digital sound, data and format are invariably coupled.  You cannot understand a data stream without an interpretation, and the format is that interpretation.

In the Sound gem, we have Device, Format, and Data objects.  A Data has to have a Format for a Device to interpret it.

    data = Data.new
    data.format = Format.new
    device = Device.new
    device.interpret data

    class Device
      def interpret(data)
        #given data.format, read data
      end
    end

A Device has no format, but it interprets Data given one.