But with Perl it's not so easy to enforce a distinction between the published API and a class's private methods. For the vast majority of published classes I've looked at, "private" methods are simply those that are not explicitly described in the official documentation. If someone finds out what these unpublished methods are, e.g. by reading the source code, he/she can use them. (Of course, this is a bad idea, but my point is that, in this common situation, Perl provides no encapsulation, other than that granted through "the kindness of strangers".)

I find accessors are useful internally, for the same reason they are useful externally: they provide insulation against whatever changes may affect the implementation of a state variable. Therefore, even when I don't publish most accessors, I like to have plenty of them (I usually give these "private" accessors names that begin with _, FWIW).

Of course, I could do the "lexical accessors" trick (i.e. implement accessors as coderefs stored in lexical variables), but this is problematic in two ways. One is that subclasses cannot inherit these accessors, which, more often than not is a PITA. And two, I can't directly test these "lexical accessors" in my test suite.

As always, I look forward to reading your comments.