# By alan snape
# All rights reserved.

class Class
  def attr_accessor_with_history(attr_name)
    attr_name = attr_name.to_s # make sure it's a string
    attr_reader attr_name # create the attribute's getter
    attr_reader attr_name+"_history" # create bar_history getter
    class_eval %Q|
      @#{attr_name} = nil
      @#{attr_name}_history = nil
      def #{attr_name}
        @#{attr_name}
      end
      def #{attr_name}=(value)
        if @#{attr_name} then
          @#{attr_name}_history.push(@#{attr_name})
        else
          @#{attr_name}_history = [@#{attr_name}]
        end
        @#{attr_name} = value
      end
      def #{attr_name}_history
        @#{attr_name}_history
      end
    |
  end
end