# File lib/ruport/data/table.rb, line 618
    def sort_rows_by(col_names=nil, &block)
      # stabilizer is needed because of 
      # http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/170565
      stabilizer = 0

      data_array =
        if col_names
          sort_by do |r| 
            stabilizer += 1
            [Array(col_names).map {|col| r[col]}, stabilizer] 
          end
        else
          sort_by(&block)
        end

      table = self.class.new( :data => data_array, 
                              :column_names => @column_names,
                              :record_class => record_class )

      return table
    end