__autoload

(PHP 5, PHP 7)

__autoload — 尝试加载未定义的类

Warning

本函数已自 PHP 7.2.0 起被废弃，并自 PHP 8.0.0 起被移除。 强烈建议不要依赖本函数。

说明

__autoload ( string $class ) : void

你可以通过定义这个函数来启用类的自动加载。

参数

class

待加载的类名。

返回值

没有返回值。

参见

User Contributed Notes

sham dot hrm at gmail dot com 14-Mar-2021 06:18
We you create an object of the class and If the PHP engine doesn't find the class file included in the script then __autoload() magic method will automatically trigger.

You can implement it as given below example:

<?PHP
function __autoload($ClassName)
{
    include($ClassName.".php");
}
$obj = new Base;
?>
ohcc at 163 dot com 29-Nov-2017 05:51
In PHP 7.2, this code will trigger a "
Deprecated: __autoload() is deprecated, use spl_autoload_register() instead in path\to\file.php on line *" error although the spl_autoload_register function really really exists.
<?php
    if(!function_exists('spl_autoload_register')){
        function __autoload($class){
            // blah blah blah
        }
    }
?>
Jose G 04-Dec-2014 08:29
You should use include() or require() inside __autoload()
instead of include_once() or require_once().

If you reach __autoload(), then you know the file with the class definition has not been loaded yet.

include() and require() are more efficient than include_once() and require_once().
Ben 26-Mar-2014 05:56
Guys, this document ( i mean __autoload() ) not mentioned one special situation: if you both use __autoload() and spl_autoload_register(), the __autoload() function will never to be called. Although spl_autoload_register() documentation explained why, i decide to wrote this in case some one get confused and waste all day to figure out why.

Here is some code to verify above:

<?php
function __autoload($class) {
}

function my_loader() {
}

function your_loader() {
}

var_dump ( spl_autoload_functions () );
echo '<br/>';

spl_autoload_register ( 'my_loader' );
spl_autoload_register ( 'your_loader' );

var_dump ( spl_autoload_functions () );
ohcc at 163 dot com 08-Dec-2013 07:12
It is highly recommended not to use the __autoload() function any more. Now the spl_autoload_register() function is what you should consider.
<?php
    if(!function_exists('classAutoLoader')){
        function classAutoLoader($class){
            $class=strtolower($class);
            $classFile=$_SERVER['DOCUMENT_ROOT'].'/include/class/'.$class.'.class.php';
            if(is_file($classFile)&&!class_exists($class)) include $classFile;
        }
    }
    spl_autoload_register('classAutoLoader');
?>
eragroove at gmail dot com 10-Jul-2013 05:48
If you can keep file name and class name as same, it will be good programming practice. It helps to __autoload function to load file without checking any condition.
 
function __autoload($class){
  require_once( $class.".php");
}
qeremy 08-Mar-2012 03:01
Even I have never been using this function, just a simple example in order to explain it;

./myClass.php
<?php
class myClass {
    public function __construct() {
        echo "myClass init'ed successfuly!!!";
    }
}
?>

./index.php
<?php
// we've writen this code where we need
function __autoload($classname) {
    $filename = "./". $classname .".php";
    include_once($filename);
}

// we've called a class ***
$obj = new myClass();
?>

*** At this line, our "./myClass.php" will be included! This is the magic that we're wondering... And you get this result "myClass init'ed successfuly!!!".

So, if you call a class that named as myClass then a file will be included myClass.php if it exists (if not you get an include error normally). If you call Foo, Foo.php will be included, and so on...

And you don't need some code like this anymore;

<?php
include_once("./myClass.php");
include_once("./myFoo.php");
include_once("./myBar.php");

$obj = new myClass();
$foo = new myFoo();
$bar = new myBar();
?>

Your class files will be included "automatically" when you call (init) them without these functions: "include, include_once, require, require_once".