car.rb

module Lib
  def self.my_attr_accessor(klass, attr)
    klass.class_eval "def #{attr.to_s}; @#{attr.to_s}; end"
    klass.class_eval "def #{attr.to_s}=(arg); @#{attr.to_s} = arg; end"
  end
end
 
class Car
  Lib::my_attr_accessor(self, 'color')
end
 
c = Car.new
c.color = 'rood'
puts c.color #=> 'rood'

c.color = 'groen'
puts c.color #=> 'groen'

puts "Hooray!!!!" #=> 'Hooray!!!!'