gistfile1.php

<?php

class Foo
{
	public $bar;

	public function __construct()
	{
		$this->update(5);
	}
	
	public function update($x)
	{
		$this->bar = new Bar;
		$this->bar->x = $x;
	}
	
	public function &getBar()
	{
		return $this->bar;
	}
}

class Bar
{
	public $x;
}

$foo = new Foo;
$bar =& $foo->getBar();
var_dump($bar->x);
$foo->update(11);
var_dump($bar->x);