That is a wise question, another is which modules to avoid.

Over the years I have had cause to read and understand some CPAN modules, either because I was stepping into them with a debugger, or because I was trying to discover if the bug I was seeing was mine, or came from a module I was using.

Some modules are very readable, but others are horrible, most commonly with a very compact style of code that looks like line noise and gives us a bad reputation. I can't remember any specific examples, and even if I could I would not name them here, because as far as I m concerned, if the code works and someone else is taking responsibility for maintenance, then I don't care about the style, but for a beginner reading code and trying to learn from it, then it would be good to warn the beginner that here be dragons.