If you use a module, Perl deals with it at compile time. If you require a module, Perl deals with it at run time.

I typically like to use a module because it allows me to check everything via a perl -c someprog.pl after I've finished coding. It I used require instead, I wouldn't find out that something was wrong until I ran the program for the first time. YMMV, just my own personal preference.

require is handy though if your program needs to do something based on whether you have a module installed on your system. You can test for this at runtime.

#!/usr/bin/perl -w

use strict;

# do we have FOO::Bar on this system?
eval { require FOO::Bar };
if ($@) {
   # FOO::Bar not installed
} else {
   # FOO::Bar installed
}

[download]
-- vek --

In reply to Re^3: Program structure: subs vs modules vs Selfloader by vek
in thread Program structure: subs vs modules vs Selfloader by bradcathey

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.