The difference between spl_autoload_register() and __autoload(), spl_autoloadregister_PHP tutorial

The difference between spl_autoload_register() and __autoload(), splautoloadregister

This article mainly introduces the difference between spl_autoload_register() and __autoload(). Friends in need can refer to it. ​

Regarding spl_autoload_register() and __autoload(), I believe most people will choose the former? Look at the usage of both:

Copy codeThe code is as follows:
//__autoload usage
function __autoload($classname)
{
$filename = "./class/".$classname.".class.php";
if (is_file( $filename))
{
include $filename;
}
}

//spl_autoload_register usage
spl_autoload_register('load_class');

function load_class($classname)
{
$filename = "./class/".$classname.".class.php";
if (is_file($filename))
{
include $filename;
}
}

The benefits of using spl_autoload_register() are indescribable:
(1) Automatically loading objects is more convenient, and many frameworks do this:

Copy codeThe code is as follows:
class ClassAutoloader {
public function __construct() {
spl_autoload_register(array($this, 'loader'));
}
private function loader($className) {
echo 'Trying to load ', $className, ' via ', __METHOD__, "()n";
include $className . '.php';
}
}

$autoloader = new ClassAutoloader();

$obj = new Class1();
$obj = new Class2();

(2) You need to know that the __autoload() function can only exist once. Of course, spl_autoload_register() can register multiple functions

Copy codeThe code is as follows:
function a () {
include 'a.php';
}
function b () {
include 'b.php';
}
spl_autoload_register(' a');
spl_autoload_register('b');

(3) SPL functions are rich and provide more functions, such as spl_autoload_unregister() to unregister registered functions, spl_autoload_functions() to return all registered functions, etc.

​
See the PHP Reference Manual: About the SPL function list.

Note:

If the __autoload function has been implemented in your program, it must be explicitly registered to the __autoload stack middle. Because the
spl_autoload_register() function will replace the __autoload function in Zend Engine with spl_autoload() or spl_autoload_call()

Copy codeThe code is as follows:
/**
*__autoload method will be invalid after spl_autoload_register, because the autoload_func function pointer already points to the spl_autoload method
* You can add the _autoload method to the autoload_functions list by the following method
*/
spl_autoload_register( '__autoload' );

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