Question

I want to do this:

class T
{
    public $a;
    public $b;
    public function __construct()
    {
        $this->a = new P;
        $this->b = clone $this->a;
    }
}

class P
{
    public $name ="Chandler";
    public function __clone()
    {
        $this->name = & $that->name;
    }

}

$tour = new T;
$tour->a->name = "Muriel";

?>

But after this, $tour->b->name will be NULL, why ?
How can I make the clone name property reference to the parent object name property, so when I change the parent object name, the cloned object name will change accordingly ?

Answer 1

$that doesn’t exist in the __clone function as said in George Schlossnagle: Advanced PHP Programming book… It gave me a couple of weeks headache…
So, you can do this with a simple trick in the constructor (in class P); make the variable reference to himself:

function __construct()
{
    $this->name = & $this->name;
}

this works in PHP 5.3.6. I did not test it in other versions.
So when you do $tour->a->name = "Muriel";, then $tour->b->name will be “Muriel” too!