SPL Functions
PHP Manual


(PHP 5 >= 5.1.2, PHP 7)

spl_autoload_registerRegister given function as __autoload() implementation


bool spl_autoload_register ([ callable $autoload_function [, bool $throw = true [, bool $prepend = false ]]] )

Register a function with the spl provided __autoload queue. If the queue is not yet activated it will be activated.

If your code has an existing __autoload() function then this function must be explicitly registered on the __autoload queue. This is because spl_autoload_register() will effectively replace the engine cache for the __autoload() function by either spl_autoload() or spl_autoload_call().

If there must be multiple autoload functions, spl_autoload_register() allows for this. It effectively creates a queue of autoload functions, and runs through each of them in the order they are defined. By contrast, __autoload() may only be defined once.



The autoload function being registered. If no parameter is provided, then the default implementation of spl_autoload() will be registered.


This parameter specifies whether spl_autoload_register() should throw exceptions when the autoload_function cannot be registered.


If true, spl_autoload_register() will prepend the autoloader on the autoload queue instead of appending it.

Return Values

Returns TRUE on success or FALSE on failure.


Version Description
5.3.0 Namespaces support was introduced.
5.3.0 The prepend parameter was added.


Example #1 spl_autoload_register() as a replacement for an __autoload() function


// function __autoload($class) {
//     include 'classes/' . $class . '.class.php';
// }

function my_autoloader($class) {
'classes/' $class '.class.php';


// Or, using an anonymous function as of PHP 5.3.0
spl_autoload_register(function ($class) {
'classes/' $class '.class.php';


Example #2 spl_autoload_register() example where the class is not loaded


namespace Foobar;

Foo {
    static public function 
test($name) {
'[['$name .']]';

spl_autoload_register(__NAMESPACE__ .'\Foo::test'); // As of PHP 5.3.0

new InexistentClass;


The above example will output something similar to:

Fatal error: Class 'Foobar\InexistentClass' not found in ...

See Also

SPL Functions
PHP Manual