1<?php
2class Loader {
3	static private $loader;
4
5	static function getLoader() {
6		if (null !== self::$loader) {
7			return self::$loader;
8		}
9		return self::$loader = new Loader();
10	}
11
12	static function getCounter() {
13		static $counter = 0;
14		return $counter++;
15	}
16}
17
18class ExtLoader extends Loader {
19}
20
21Loader::getLoader();
22Loader::getCounter();
23Loader::getCounter();
24