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copied!<p><code>use</code> is equivalent to <code>BEGIN { require Module; Module->import( LIST ); }</code></p> <p>So, the main difference is that:</p> <ul> <li><p>Use is used at compile time</p></li> <li><p>Use automatically calls import subroutine (which can do <em>anything</em> but mostly used to export identifiers into caller's namespace)</p></li> <li><p>use dies if the module can not be loaded (missing/compile error)</p></li> </ul> <p><strong>As such:</strong></p> <ul> <li><p>When you need to load modules dynamically (for example, determine which module to load based on command line arguments), use <code>require</code>.</p></li> <li><p>In general, when you need to precisely control when a module is loaded, use <code>require</code> (<code>use</code> will load the module right after the preceding <code>use</code> or <code>BEGIN</code> block, <strong>at compile time</strong>).</p></li> <li><p>When you need to somehow bypass calling module's <code>import()</code> subroutine, use <code>require</code></p></li> <li><p>When you need to do something smart as far as handling load errors (missing module, module can't compile), you can wrap the <code>require</code> into an <code>eval { }</code> statement, so the whole program doesn't just die. </p> <p>You can simulate that with <code>use</code> but in rather in-elegant ways (trapping <code>die</code> signal in an early <code>BEGIN</code> block should work). But <code>eval { require }</code> is better.</p></li> <li><p>In all OTHER cases, use <code>use</code></p></li> </ul> <p>I didn't cover AUTOLOAD as that's a different beastie. Its usage is in cases when you want to intercpt calls to subroutines that you haven't imported into your namespace.</p>

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