blank_slate.rb

#---
# Excerpted from "Metaprogramming Ruby 2",
# published by The Pragmatic Bookshelf.
# Copyrights apply to this code. It may not be used to create training material, 
# courses, books, articles, and the like. Contact us if you are in doubt.
# We make no guarantees that this code is fit for any purpose. 
# Visit http://www.pragmaticprogrammer.com/titles/ppmetr2 for more book information.
#---
# Computer as a Blank Slate

class Computer < BasicObject
  # ...

  def initialize(computer_id, data_source)
    @id = computer_id
    @data_source = data_source
  end

  def method_missing(name, *args)
    super if !@data_source.respond_to?("get_#{name}_info")
    info = @data_source.send("get_#{name}_info", @id)
    price = @data_source.send("get_#{name}_price", @id)
    result = "#{name.capitalize}: #{info} ($#{price})"
    return "* #{result}" if price >= 100
    result
  end
end

require_relative 'unit_test'
require_relative 'bug_test'