Re: Static Class Member References

On 13 July 2010 09:46, Richard Quadling <rquadling@gmail.com> wrote: > On 12 July 2010 22:54, Daniel Kolbo <kolb0057@umn.edu> wrote: >> Richard Quadling wrote: >>> On 11 July 2010 23:19, Daniel Kolbo <kolb0057@umn.edu> 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