Constants usage

[Junitar]

Hello,

I was wondering if it's good practice and if it's safe to define constants that use magic constants to access various directories in a project, even directories outside the webroot. I've found many documentations that discuss how useful are constants when debugging, but what's the usual usage apart from that?

For example, is it good practice to write:

<?php
define('WEBROOT', __DIR__);
define('ROOT', dirname(WEBROOT));
define('CORE', ROOT.'/core/');
define('CONFIG', ROOT.'/config/');
define('ADMIN', ROOT.'/admin/');

include CORE.'includes/header.inc.php';

 

Edited August 1, 2017 by Junitar

[justsomeguy]

I've found many documentations that discuss how useful are constants when debugging, but what's the usual usage apart from that?

Any programming besides debugging, I suppose.  If you look at various PHP extensions or classes you'll notice that they use constants pretty extensively to provide names to values that otherwise might be meaningless.  e.g.:

http://php.net/manual/en/mysqli.constants.php

[Junitar]

Thanks for the reply. But then, what's the benefit of using, e.g. dirname(__DIR__) over $_SERVER['DOCUMENT_ROOT']?

[justsomeguy]

I don't think they will always be the same.  The document root value comes from the server's configuration file, __DIR__ is always the directory of the current script.

[Junitar]

Got it. Thank you very much!