require 'facet/kernel/nack'

class Module

  # Create an tester attribute. This creates two methods for
  # each given variable name. One is used to test
  # the attribute and the other is used to set or toggle it.
  #
  #   attr_switch :a
  #
  # is equivalent to
  #
  #   def a?
  #     @a ? true : @a
  #   end
  #
  #   def a!(switch=nack)
  #     if switch == nack
  #       @a = ! @a
  #     else
  #       @a = @a ? switch : @a
  #       self
  #     end
  #   end
  #
  def attr_tester(*args)
    make = {}
    args.each { |a|
      make["#{a}?".to_sym] = %{ def #{a}?; @#{a} ? true : @#{a}; end }
      make["#{a}!".to_sym] = %{
        def #{a}!(switch=nack)
          if switch==nack
            @#{a} = !@#{a}
          else
            @#{a} = @#{a} ? switch : @#{a}
            self
          end
        end
      }
    }
    module_eval make.values.join("\n")

    return make.keys
  end

end



#  _____         _
# |_   _|__  ___| |_
#   | |/ _ \/ __| __|
#   | |  __/\__ \ |_
#   |_|\___||___/\__|
#
# TODO