# File log4r/logger.rb, line 114
    def add(*_outputters)
      for thing in _outputters
        o = (thing.kind_of?(Outputter) ? thing : Outputter[thing])
        # some basic validation
        if not o.kind_of?(Outputter)
          raise TypeError, "Expected kind of Outputter, got #{o.class}", caller
        elsif o.nil?
          raise TypeError, "Couldn't find Outputter '#{thing}'", caller
        end
        @outputters.push o
        Logger.log_internal {"Added outputter '#{o.name}' to '#{@fullname}'"}
      end
      @outputters
    end