more_dynamic_methods.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 with define_method() and HWDataSource introspection

require_relative 'data_source'

class Computer
  def initialize(computer_id, data_source)
    @id = computer_id
    @data_source = data_source
    data_source.methods.grep(/^get_(.*)_info$/) { Computer.define_component $1 }
  end  

  def self.define_component(name)
    define_method(name) do
      # ...
      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
end

require_relative 'unit_test'