Chapter 2

If you place the preceding code in a file called Hello.pm, then you can use the module 

in a script placed in the same directory as Hello.pm:

#!/usr/bin/perl

use lib  . ;

use Hello;

Hello::greet("World");

This produces the following output:

Hello, World!

Most of the code example should look familiar, but the use lib line might be new. 

I'll explain that in the next section.

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Module Names

A module's name is its introduction. If you choose good names for your modules, 

you'll rarely have to answer the question  What does it do?  For example, pro 

grammers rarely ask me what HTML::Template does, but HTML::Pager draws 

inquiries on every mention.

Perl modules must have unique names. Having two modules with the same 

name will cause difficulties. This is similar to machines on the Internet if there 

were two Web sites called http://www.cpan.org, how would a browser know 

where to send you?

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An easy solution to the problem of finding a unique name is to use a multipart 

name. Module names can be composed of parts delimited by double colons 

(::). Most modules have names with two parts and some have three Inline::C, 

Scalar::List::Utils, Parse::RecDescent, CGI::Application. Following this practice is 

a good idea it keeps your module names short enough to easily remember. If 

you do use a long name, then you should be careful to choose a name within a 

hierarchy that will make it easy for others to find.

Many organizations use a common prefix for all their internal modules. For 

example, Vanguard Media (http://www.vm.com) creates their internal modules 

under the name  Dynexus  Dynexus::Template::File, Dynexus::Class::Base, 

and so on. This keeps the internal modules names from conflicting with names 

of externally produced modules. If you are creating private modules, you should 

consider a similar naming convention.

7. Ok, bad example round robin DNS works using this technique, but you get my point.

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