Perl Best Practices

17.10. CPAN

Use CPAN modules where feasible.

The Comprehensive Perl Archive Network (CPAN) is often referred to as Perl's killer app, and rightly credited with much of Perl's success in recent years. It is a truly vast repository of code, providing solutions for just about every programming task you might commonly encounter.

As with Perl's standard library, many of the modules on the CPAN are heavily relied-uponand severely stress-testedby the global Perl community. This makes CPAN modules like DBI, DateTime, Device::SerialPort, HTML::Mason, POE, Parse::RecDescent, SpreadSheet::ParseExcel, Template::Toolkit, Text::Autoformat, and XML::Parser extremely reliable and powerful tools. Extremely reliable and powerful free tools.

Of course, not all the code archived on CPAN is equally reliable. There is no centralized quality control mechanism for the archive; that's not its purpose. There is an integrated ratings system for CPAN modules, but it is voluntary and many modules remain unrated. So it's important to carefully assess any modules you may be considering.

Nevertheless, if your organization allows it, always check the CPAN (http://search.cpan.org) before you try to solve a new problem yourself. An hour or so of searching, investigation, quality assessment, and prototyping will frequently save days or weeks of development effort. Even if you decide not to use an existing solution, those modules may give you ideas that will help you design and implement your own in-house version.

Of course, many organizations are wary of any external software, especially if it's open source. One way to encourage your organization to allow you to use the enormous resources of the CPAN is to explain it properly. In particular don't characterize your intent as "importing unknown software"; characterize it as "exporting known development delays, testing requirements, and maintenance costs".

Another resource that may help sway your local Powers That Be is the "Perl Success Stories" archive (http://perl.oreilly.com/news/success_stories.html). Companies like Hewlett Packard, Amazon.com, Barclays Bank, Oxford University Press, and NBC are leveraging the resources of CPAN to better compete in their respective markets. Exploring their successes may cast Perl's software archive in a new and attractive pecuniary light for your boss.