The truth is that ineritance sucks. There are problems where inheritance is a good solution, but most of the time composition is a better method, and not just because it promotes encapsulation. A has-a relationship is just plain easier to code with. Even if your language provides a good mechanism for inheritance (which Perl does not) if your writing a substantial class than you'll find yourself looking under the hood 9 times out of 10.

Light a man a fire, he's warm for a day. Catch a man on fire, and he's warm for the rest of his life. - Terry Pratchet