Automatic loading mechanism for PHP classes

Automatic loading of PHP:

Before php5, we need to use a class or class method, which must include or require, before you can use, each time with a class, you have to write an include, trouble

PHP author want to Simple point, it is best to reference a class, if there is no include in, the system can automatically find the class, automatically introduced ~

Thus: the __autoload () function was born.

It is usually placed in the application entry class, such as Discuz, in the class_core.php.

Let's start with plain examples:

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);

}

}

This paragraph is thrown at the front of the entrance document, nature is very good ~

Reprint: http://www.cnblogs.com/zhongyuan/p/3583201.html

Automatic loading mechanism for PHP classes