__DIR__和自动加载php

I don't know if this is exactly a problem in autoloading, but I am having this problem, here is my code:

index.php

require __DIR__ . '/app/autoload.php';

Folder structure:

index.php
app/
--autoload.php

autoload.php

 function autoloader($className) {
    // List Directories to Autoload Classes
    $paths = array(
        __DIR__ . '/system/',
        __DIR__ . '/app/models/',
        __DIR__ . '/app/dao/'
    );
    foreach($paths as $path) {
        $file = $path . '/' . $className . '.php';
        if (is_file($file))
            include $file;
    }
}

For some reason it doesn't work even I do:

__DIR__ . '../system/
... et al.

DIR in the autoload file will refer to /app.

try:

function autoloader($className) {
    // List Directories to Autoload Classes
    $paths = array(
        '../system/',
        '/models/',
        '/dao/'
    );
    foreach($paths as $path) {
        $file = $path . '/' . $className . '.php';
        if (is_file($file))
            require_once $file;
    }
}

If that fails start echoing out paths and dir to see if they are referenced properly.

I would try it this way. Anywhere before the autoload.php is loaded (should be file which is always loaded, i guess in your case its index.php) i would define ROOT variable somwhere at begining of the script

/**
* Use the DS to separate the directories (just a shortcut)
*/
if (!defined('DS')) {
   define('DS', DIRECTORY_SEPARATOR);
}

/**
* The full path to the directory which holds application files, without a trailing DS.
*/
if (!defined('ROOT')) {
    define('ROOT', dirname(__FILE__)); 
}

and then in your autoload use ROOT

$paths = array(
    ROOT . DS. 'system' . DS,
    ROOT . DS. 'app' . DS . 'models' . DS,
    ROOT . DS. 'app' . 'dao' . DS
);