#6193 [Ana->Csd]: new object makes a shallow copy
| From: | tony2001@php.net | Date: | Mon, 03 Apr 2006 07:36:56 +0000 |
| Subject: | #6193 [Ana->Csd]: new object makes a shallow copy | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-95232@lists.php.net to get a copy of this message | ||
ID: 6193
Updated by: tony2001@php.net
Reported By: Heinz at chanet dot de
-Status: Analyzed
+Status: Closed
Bug Type: Feature/Change Request
Operating System: Win2000
PHP Version: 4.0.1pl2
New Comment:
Fixed in PHP5.
Previous Comments:
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[2000-08-17 08:46:03] waldschrott@php.net
urgs, that´s a pity - there´s some unexpected behaviour
using references, we should document this unless it´s not
improved...
------------------------------------------------------------------------
[2000-08-17 04:30:49] stas@php.net
From the talk with Andi it seems that there's no way to do the thing
you wnt in PHP, because reference is not a pointer, it's a binding
between two variables. SO I move it to feature requests.
------------------------------------------------------------------------
[2000-08-16 07:55:18] waldschrott@php.net
3) possibly related, just realized that this does not work too...
class CTest {
var $v=9;
function ®() {
return $this; } }
$myobj= new CTest();
$register_object=$myobj->reg();
var_dump($register_object);
------------------------------------------------------------------------
[2000-08-16 07:48:49] waldschrott@php.net
Right, that´s two bugs here... the only proper way I know of to
workaround this is to reference them outside, like this:
$x = new A();
$c_x = &$x;
1) neither copying nor referencing works in this case inside the
constructor, I remember this as a possibly known issue...
2) re-referencing does not work... I´ve moved that linking process to
another method (not constructor)
- both referencing AND copying works *inside* CTest->Reg, but zend
fails to recognize that $reg is already a reference, thus it is not
visible outside
I think even this is a known issue, not sure
$register_object;
class CTest {
var $v=9;
function CTest() { }
function reg(&$reg) {
$reg=$this;
var_dump($reg); }
}
$myobj= new CTest();
$myobj->reg($register_object);
var_dump($register_object);
$myobj->v= 1;
$register_object->v= 2;
echo 'both should be equal: ', $myobj->v, ' ',
$register_object->v;
------------------------------------------------------------------------
[2000-08-16 07:28:09] Heinz at chanet dot de
The new object function seems to generate the object twice. This is a
quite unexpected oo feature and it could be a performance bottleneck
for complex classes!
test script:
<?
$register_object;
class CTest {
var $v;
function CTest(&$reg) {
$reg= $this;
// no difference for: $reg= &$this;
}
}
$myobj= new CTest($register_object);
$myobj->v= 1;
$register_object->v= 2;
echo 'both should be equal: ', $myobj->v, ' ',
$register_object->v;
?>
I would assume that $myobj and $register_object are the same class
instance, but this is not true.
Ok, this example is stupid, but assume CTest is a shopping_item and
$register_object is a shopping_card.
The shopping item in the constructer tries to register itself in the
shopping cart. Doesn't this makes sense?
In general it's from the SW design point of view critical to handle
objects as values and not as refernces.
Ok, you introduced in PHP4 the & operator but I've not found how to
specify the & operator for the new function.
Thanks in advance
Heinz
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/?id=6193&edit=1