To module or not?

[bradcathey]

Fellow Monasterians,

I need a little help to understand the importance of using a module in it's official form or not. Thanks to tachyon's tutorial I've successfully coded my first working module.

package MyModule2; #line 1

use strict;
use Exporter;
our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);

$VERSION     = 1.00;
@ISA         = qw(Exporter);
@EXPORT      = ();
@EXPORT_OK   = qw(add_it);
%EXPORT_TAGS = ( All  => [qw(&add_it)]); # line 11

sub add_it { 
   my $amount = shift;
   my $total = 12+ $amount;
   return ($total);
}
1;

Which is called by:

#!/usr/bin/perl -w

print "Content-type: text/html\n\n";
#use lib "/home/jdsakroc/public_html/admin/cgi-bin";
use strict;
use warnings;
use CGI::Carp qw(fatalsToBrowser);
use MyModule2 qw(:All);

my $amount = 12;

print add_it($amount),"\n";

But, the following works as well (minus the first 11 lines of orig.)

sub add_it { 
   my $amount = shift;
   my $total = 12+ $amount;
   return ($total);
}
1;

Which is called by:

use MyModule;

my $amount = 12;

print add_it($amount),"\n";

Question is: What is the point of creating the module with all the header stuff, when I can just save the function in a ______.pm file and use it like that? How clueless is this? Thanks!

Update: Thanks all, I'm getting it now ;-) In one word: "namespace." I can see how similiarly named functions would collide if the namespace was the same.