Richard Quadling wrote:
> On 13 July 2010 09:46, Richard Quadling <rquadling@xxxxxxxxx> wrote:
>> On 12 July 2010 22:54, Daniel Kolbo <kolb0057@xxxxxxx> wrote:
>>> Richard Quadling wrote:
>>>> On 11 July 2010 23:19, Daniel Kolbo <kolb0057@xxxxxxx> wrote:
>>>>> Hello PHPers,
>>>>>
>>>>> I'm having some trouble understanding some PHP behaviour. The following
>>>>> example script exhibits the behaviour which I cannot understand.
>>>>> [code]
>>>>> <?php
>>>>>
>>>>> class A
>>>>> {
>>>>> public static $a = 3;
>>>>>
>>>>> function __construct()
>>>>> {
>>>>> //self::$a = $this; //[i]
>>>>> self::$a =& $this; //[ii]
>>>>> }
>>>>> }
>>>>>
>>>>> class B extends A
>>>>> {
>>>>> function __construct()
>>>>> {
>>>>> parent::__construct();
>>>>> }
>>>>> }
>>>>>
>>>>> class C {
>>>>> var $c;
>>>>>
>>>>> function __construct()
>>>>> {
>>>>> $this->c =& A::$a;
>>>>> }
>>>>>
>>>>> }
>>>>>
>>>>>
>>>>> $c = new C;
>>>>> $b = new B;
>>>>> $cee = new C;
>>>>>
>>>>> var_dump($c->c); // [i] prints object(B), but [ii] prints int 3
>>>>> var_dump($cee->c); // [i] prints object(B), and [ii] prints object(B)
>>>>>
>>>>> ?>
>>>>> [/code]
>>>>>
>>>>> Why does $c->c print 'int 3' ?
>>>>>
>>>>> I'm nervous to use "self::$a = $this;" because I don't want to be
>>>>> copying the whole object. However, isn't $this just a reference to the
>>>>> object, so "self::$a = $this;" is just copying the reference and not the
>>>>> actual object, right?
>>>>>
>>>>> Thanks in advance
>>>>
>>>> What do you think the value should be?
>>>>
>>>> A static property is bound to the class and not to an instance of the class.
>>>>
>>>> So, &A::$a is a reference to the static value. If you alter the value,
>>>> it will be altered for a subclasses of A and for any other reference
>>>> to it.
>>>>
>>> I think
>>> var_dump($c->c); would print object(B), but it's printing int 3.
>>>
>>> The reference is *not* being updated. I think this is a bug. What do
>>> you think?
>>>
>>> Thanks
>
> Aha!
>
> $c = new C;
>
> At this stage $c->c will be a reference to the static A::$a = 3.
>
> $b = new B;
>
> Now, as B's constructor calls A's constructor which replaces the
> static A::$a with a reference to the instance $b, the static A::$a
> should now be $b
>
> $cee = new C;
>
> At this stage $cee->c will be a reference to the static A::$a = $b.
>
> But, when var_dump()'d, $c->c !== $cee->c, and I think they should as
> both have been assigned to a reference of a static.
>
> It would seem to be a bug.
>
> I get the same output for V5.0.0 to V5.3.3RC2
>
Thanks for confirming. I reported the bug. I shortened up the test
script quite a bit. Please see: Bug #52332
http://bugs.php.net/bug.php?id=52332
`
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