Are PHP5 objects passed by reference?

Question

I can\'t seem to get any consistent info on this. Different sources appear to say different things and the venerable php.net itself (appears) not to explicitly stat

Answer 1

Just an example where passing "objects" by reference is useful:

class RefTest1
{
    public $foo;

    public function __construct(RefTest2 &$ref = null)
    {
        $this->foo =& $ref;
    }
}

class RefTest2
{
    public $foo;

    public function __construct(RefTest1 &$ref = null)
    {
        $this->foo =& $ref;
    }
}

class RefTest3
{
    public $foo;

    public function __construct(RefTest2 &$ref = null)
    {
        $this->foo =& $ref;
    }
}

class DoCrossRef
{
    public $refTest1;
    public $refTest2;

    public function __construct()
    {
        $this->refTest1 = new RefTest1($this->refTest2);
        $this->refTest2 = new RefTest2($this->refTest1);
    }

    public function changeReference()
    {
        $this->refTest1 = new RefTest3($this->refTest2);
    }
}

At the end RefTest1 holds a reference to RefTest2 and the other way around, also if the RefTest2 object did not exist at the time RefTest1 was created.

After calling DoCrossRef->changeReference(), the RefTest2 objects also holds a reference to the new RefTest3 object.