update_attributes

# File lib/rdoc/ri/ri_formatter.rb, line 569
    def update_attributes(current, wanted)
      str = ""
      # first turn off unwanted ones
      off = current & ~wanted
      for quality in [ BOLD, ITALIC, CODE]
        if (off & quality) > 0
          str << "</" + ATTR_MAP[quality]
        end
      end

      # now turn on wanted
      for quality in [ BOLD, ITALIC, CODE]
        unless (wanted & quality).zero?
          str << "<" << ATTR_MAP[quality]
        end
      end
      print str
    end