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POWhy use short-circuit code?
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copied!<p><em>Related Questions</em>: <a href="https://stackoverflow.com/questions/89154/benefits-of-using-short-circuit-evaluation">Benefits of using short-circuit evaluation</a>, <a href="https://stackoverflow.com/questions/1445867/why-would-a-language-not-use-short-circuit-evaluation">Why would a language NOT use Short-circuit evaluation?</a>, <a href="https://stackoverflow.com/questions/1732403/can-someone-explain-this-line-of-code-please-logic-assignment-operators">Can someone explain this line of code please? (Logic & Assignment operators)</a></p> <p>There are questions about the benefits of a language using short-circuit code, but I'm wondering what are the benefits for a programmer? Is it just that it can make code a little more concise? Or are there performance reasons?</p> <p>I'm not asking about situations where two entities need to be evaluated anyway, for example:</p> <pre><code>if($user->auth() AND $model->valid()){ $model->save(); } </code></pre> <p>To me the reasoning there is clear - since both need to be true, you can skip the more costly model validation if the user can't save the data.</p> <p>This also has a (to me) obvious purpose:</p> <pre><code>if(is_string($userid) AND strlen($userid) > 10){ //do something }; </code></pre> <p>Because it wouldn't be wise to call <code>strlen()</code> with a non-string value.</p> <p>What I'm wondering about is the use of short-circuit code when it doesn't effect any other statements. For example, from the Zend Application default index page:</p> <pre><code>defined('APPLICATION_PATH') || define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); </code></pre> <p>This could have been:</p> <pre><code>if(!defined('APPLICATION_PATH')){ define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); } </code></pre> <p>Or even as a single statement:</p> <pre><code>if(!defined('APPLICATION_PATH')) define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../application')); </code></pre> <p>So why use the short-circuit code? Just for the 'coolness' factor of using logic operators in place of control structures? To consolidate nested if statements? Because it's faster?</p>

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