module Sandbox

def self.add_attributes(klass, *attrs)
  self.const_get_from_string(klass).class_eval do
    attr_accessor *attrs
    # set up the 'initialize' method to assign the attributes
    define_method(:initialize) do |value_hash={}|
      attrs.each_with_index do |attr|
        instance_variable_set("@#{attr}", value_hash[attr.to_sym])
      end
    end
  end
end