A Private Stash (of modules) - Page 168

After installing modules with reckless abandon, we've probably sufficiently populated ~lonelyone/perl/modules by now. The last link in the chain is convincing Perl, which would not normally otherwise, to look here to find these modules. Perl, like most of us, is egocentric. If you don't grab its head and make it look at you, it'll look at its own navel.

So, the very typical approach to a Perl script:

#!/usr/bin/perl
use DBI;
use Create::PDF;

Its going to choke, because Perl will look in its own navel to find the modules DBI and Create::PDF. When Perl coughs up a lung over a missing module, it looks quite like this (squeamish? turn away):

Can't locate DBI.pm in @INC
  (@INC contains: /usr/local/lib/perl5/5.6.1/i686-linux
/usr/local/lib/perl5/5.6.1
  /usr/local/lib/perl5/site_perl/5.6.1/i686-linux
/usr/local/lib/perl5/site_perl/5.6.1
  /usr/local/lib/perl5/site_perl/5.6.0/i686-linux
/usr/local/lib/perl5/site_perl/5.6.0
  /usr/local/lib/perl5/site_perl .) at test.pl line 6.
BEGIN failed—compilation aborted at test.pl line 6.

[Lines 1 and 2 above are one line as are lines 3 and 4, 5 and 6, and 7 and 8. They have been split for formatting purposes.]

It's a big, ugly error. Perl is saying, I've looked all over for DBI.pm (module scripts end in .pm) and can't find it anywhere (anywhere, by the way, happens to be the following places). What we need to do is tell Perl where we've stashed our modules.

Our example has assumed that our Perl scripts would reside in ~lonelyone/perl and the modules would be in ~lonelyone/perl/modules. In that case, one small addition to our script will point Perl's head in the right direction.

#!/usr/bin/perl
use lib './modules';
use DBI;
use Create::PDF;

Of course, depending on the relationship between the location of your Perl scripts, and your Perl modules, you would need to adjust the "use lib" path accordingly. Additionally, you can add several "use lib" lines if you have more than one location that you want Perl to seek for modules.

A Good Yield

Thanks to the CPAN module, you can now browse about the comprehensive set of Perl modules in one centralized hoe-down of a farmer's market. Being limited to your own home directory on a host's server needn't be limiting at all, now that you see how to retrieve, install, and include additional Perl modules at your heart's content.

Of course, CPAN is available on the Web, too. Consult their Web-based search to browse the module archive from a browser, which some prefer to help track down a module of choice. You can then turn to the CPAN shell to invoke the installation.

They Shoot Coders, Don't They? - Page 167
The Perl You Need to Know Part 23: CPAN, a Farmer's Market for Perl - Page 164
The Perl You Need to Know Part 24: Introduction to Object Oriented Perl - Page 169