Sometimes it depends on your user interfaces to your object. Perl's oop, on a basic level, has no security behind it, so any method you use for changing an attribute or state of an object for your factory, is available to the developer using your object. When you maintain state internally to your object, that may be a bad thing. i.e. if you have a linklist like object, and you create a method called set_size which just sets an internal variable for get_size to report back a number, some chucklehead, wrongly, and idiotically, if not documented, may try and use this method. Now your get_size will be off. But as they say, if you have no buisness being there, don't be surprised if I have a shotgun. :)

I only raise the point, as some other OOP implementations, java, ruby, python, c++, have different levels of encapsulation ability and security. In perl, it may be a silly thing, but in others, it may matter more.

cheers