getxml in DB_Result

Hi this morning was a message on the phplib-list, that someone wrote an getxml function into the db-abstraction of phplib. cool idea. so i wrote i quick implentation into DB.php (see attachement for the diff, the function goes into DB_Result). at our company, we write at the moment some classes which translate sql-query into xml. a little bit more complex than the example above, so expect more of this stuff to come. maybe we can also have a discussion about that here (how to do it, what's needed, etc..) and one thing more, maybe this was discussed already, but i find it quite unclear, why the rule one class = one file is not used on everything in pear. it's not very overviewable if there are more than one class in one file (like in DB.php and PEAR.php). are there any reasons, this is not done everywhere? chregu