spl_autoload_register

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

spl_autoload_register — Register given function as __autoload() implementation

Description

spl_autoload_register(?callable$callback = null, bool$throw = true, bool$prepend = false): bool

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.

Parameters

callback

The autoload function being registered. If null, then the default implementation of spl_autoload() will be registered.

callback(string$class): void

The class will not contain the leading backslash of a fully-qualified identifier.

throw

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

Warning

This parameter is ignored as of PHP 8.0.0, and a notice will be emitted if set to false. spl_autoload_register() will now always throw a TypeError on invalid arguments.

prepend

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.

Changelog

Version	Description
8.0.0	`callback` is now nullable.

Examples

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

<?php

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

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

spl_autoload_register('my_autoloader');

// Or, using an anonymous function
spl_autoload_register(function ($class) {
 include 'classes/' . $class . '.class.php';
});

?>

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

<?php

namespace Foobar;

class Foo {
 static public function test($class) {
 print '[['. $class .']]';
 }
}

spl_autoload_register(__NAMESPACE__ .'\Foo::test');

new InexistentClass;

?>

The above example will output something similar to:

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

Example #3 The identifier will be provided without the leading backslash

<?php

spl_autoload_register(static function ($class) {
var_dump($class);
});

class_exists('RelativeName');
class_exists('RelativeName\\WithNamespace');
class_exists('\\AbsoluteName');
class_exists('\\AbsoluteName\\WithNamespace');

?>

The above example will output:

string(12) "RelativeName" string(26) "RelativeName\WithNamespace" string(12) "AbsoluteName" string(26) "AbsoluteName\WithNamespace"