Sams Teach Yourself PHP in 24 Hours, Third Edition

Automatically Loading Include Files with ___autoload()

In a large project, code files tend to fill up with calls to include_once(). Very often, you will find that you are loading many files unnecessarily as you copy around amended source files. By the same token, you waste time adding include_once() calls to class files, only to run the script and discover that more files need including. PHP 5 provides the built-in __autoload() function, which is automatically called whenever you try to instantiate an nonexistent class. __autoload() is passed a string variable representing the class name that was not found. You can then use this string to include a source file:

 <?php function ___autoload ($class) { $file = "$class.inc.php"; include_once( $file ...