Autoloader.php

<?php
/**
 * Autoloader
 */


// Define some useful constants
if(!defined('DS'))
	define('DS', DIRECTORY_SEPARATOR);
if(!defined('PS'))
	define('PS', PATH_SEPARATOR);

// Set up an array with the directories we'll use for inclusions
$directories = array_map(function($path) {
	$path = str_replace('/', DS, $path);
	return dirname(__FILE__).DS.$path;
},
// We'll look in these directories for the classes
array(
	'app/controller',
	'app/model',
	'app/view',
	'app/plugins',
	'app/lib'
));

set_include_path(
	get_include_path().
	PS.
	implode(PS, $directories)
);

spl_autoload_register(function($classname) {
	$classfile = $classname.'.php';
	if(file_exists($classfile))
		require_once $classfile;
});