<?php
class Registry 
{
	static $entries = array();
	
	static function getEntry($name) {
		return self::$entries[$name];
	}
	
	static function setEntry($name, $value) {
		self::$entries[$name] = $value;
	}
}

// použití
Registry::setEntry("master", new Db("master"));
$master = Registry::getEntry("master");