An in-depth understanding of the automatic loading mechanism of PHP classes

The first case: the contents of the file a.php are as follows

<?php
Class a{
Public Function __construct () {
echo ' FFF ';
}
}
?>

The contents of the file c.php are as follows:

<?php
function __autoload ($class)
{
$file = $class. '. php ';
if (Is_file ($file)) {
Require_once ($file);
}
}
$a = new A (); This side will automatically call __autoload, introduce the a.php file
?>

Second situation: Sometimes I want to be able to customize AutoLoad, and want to play a cooler name loader, then c.php to read as follows:

<?php
function Loader ($class)
{
$file = $class. '. php ';
if (Is_file ($file)) {
Require_once ($file);
}
}
Spl_autoload_register (' loader '); Register an automatic loading method that overwrites the original __autoload
$a = new A ();
?>

The third case: I want to be tall on a bit, using a class to manage automatic loading

<?php
Class Loader
{
public static function LoadClass ($class)
{
$file = $class. '. php ';
if (Is_file ($file)) {
Require_once ($file);
}
}
}
Spl_autoload_register (Array (' Loader ', ' loadclass '));
$a = new A ();
?>

Current is the best form.

Usually we put spl_autoload_register (*) in the portal script, which is quoted in the beginning. For example, the following discuz practice.

if (function_exist (' Spl_autoload_register ')) {
Spl_autoload_register (Array (' core ', ' autoload ')); If there is a registration function above PHP5, then registering the AutoLoad in the core class you wrote is the auto-load function
}else{
function __autoload ($class) {//If not, rewrite the PHP native function __autoload function to invoke its own core function.
Return Core::autoload ($class);
}
}

An in-depth understanding of the automatic loading mechanism of PHP classes