Now that we understand OOD in Perl, we
are ready to discuss another addition to the Perl universe
made by Perl 5: Modules.
Perl 5 Modules are similar to Perl 4
required libraries in that they provide shared resources.
However, in the case of Modules, what is being shared is
more than simple subroutines, but actual objects. Modules
are classes that define objects that may be accessed by other
For instance, our cat class could be
made into a module. And then it could be used by other
To make a module, all we need to do is
give it a .pm extension and make sure it is visible to any
perl application that needs to use it. Once that is done,
the module is ready to use.