Chapter 7: Great CPAN Modules

Chapter 7 - Great CPAN Modules
by?Sam Tregar?
Apress ? 2002
Companion Web Site

Overview

CPAN HOUSES A WIDE VARIETY of modules, from 10-line modules created by a single author to massive 10,000-line multifile modules created by teams of programmers. In fact, size and complexity are just one measure of variety in CPAN modules. Along every conceivable axis—design, documentation, implementation, testing, packaging—there exists great variety. CPAN is a virtual jungle teeming with biodiversity.

And, like a real jungle, CPAN hosts a struggle for survival. Modules on CPAN don't compete for food and shelter, but they do compete for equally scarce resources: users and developers. Open-source projects depend on users to grow and evolve. Without a group of users and at least one dedicated developer, even the best module on CPAN will soon find itself growing obsolete.

Of course, failure in this struggle isn't quite as perilous as it is in the real world; modules that fail to find a user community are never killed.^[1] Also, it must be stressed that although modules are pitted in competition, their authors are not. Nearly every CPAN author has a couple duds in their module directories, but that doesn't detract from the success of their better works.

This chapter will examine the properties of a "great" CPAN module by examining particularly successful modules. These modules have attracted large numbers of users and are often supported by a number of programmers. Since CPAN doesn't collect statistics on module usage,^[2] I've chosen modules to look at based on my own experience as a CPAN user. There are, of course, many excellent modules that I didn't have the time to include.

One of the best ways to learn how to create great CPAN modules is to read other great modules. Consider this chapter an annotated reading list and you'll be well on your way.

^[1]Although some people think they should be! As Lincoln Stein, author of the CGI and GD modules, put it when asked what changes he would like to see in CPAN, "Purge the cruft!"

^[2]See the CPAN FAQ for an answer to the question, "Why not?"