#24630 [Fbk->Opn]: extract with EXTR_REFS makes weird references
| From: | tater at potatoe dot com | Date: | Sun, 13 Jul 2003 04:10:34 +0000 |
| Subject: | #24630 [Fbk->Opn]: extract with EXTR_REFS makes weird references | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-43859@lists.php.net to get a copy of this message | ||
ID: 24630
User updated by: tater at potatoe dot com
Reported By: tater at potatoe dot com
-Status: Feedback
+Status: Open
Bug Type: Zend Engine 2 problem
Operating System: OS X 10.2
PHP Version: 5.0.0b2-dev
New Comment:
But '$b = array('x'=>&$a);' is quite different from
'$b = array('x'=>$a);', and extract() is retroactively
altering the definition of $b. $b['x'] should just be a copy
of $a. I think it's just a symbol table problem. If I do:
$a = 10;
$b['x'] = $a;
$a = 10;
extract($b, EXTR_REFS);
$x = 5;
now $a is not changed. If $b['x'] really was &$a, that would not be the
case.
Previous Comments:
------------------------------------------------------------------------
[2003-07-12 22:34:23] sniper@php.net
IMO, it's exactly how it's supposed to work.
To emulate the EXTR_REFS:
<?php
function trap1()
{
$a = 10;
$b = array('x'=>&$a);
$x =& $b['x'];
$x = 5;
var_dump(get_defined_vars());
}
trap1();
------------------------------------------------------------------------
[2003-07-12 21:40:25] tater at potatoe dot com
OK, tell me this is bogus:
-------------------------------
<?php
function trap1()
{
$a = 10;
$b = array('x'=>$a);
$x =& $b['x'];
$x = 5;
var_dump(get_defined_vars());
}
trap1();
function trap2()
{
$a = 10;
$b = array('x'=>$a);
extract($b, EXTR_REFS);
$x = 5;
var_dump(get_defined_vars());
}
trap2();
?>
In first function, $a is unchanged. In second, it is altered. They
should behave the same way. It is only
extract() making the difference.
------------------------------------------------------------------------
[2003-07-12 21:04:27] sniper@php.net
Try search the bug database before submitting new reports..
there are couple of related reports still open. (mostly documentation
issues..)
------------------------------------------------------------------------
[2003-07-12 20:47:59] tater at potatoe dot com
Description:
------------
If you create an array by assigning its elements the value of a scalar
variable (or, in PHP5, by using array_combine() with an array of keys
and an array built with array_fill() or array_pad()), then
extract(array, EXTR_REFS) will make that scalar into a reference, as
well as making all the array elements references to the same...
location? I don't know, they all end up pointing to the same thing, so
that changing any one of them changes all of them.
This tests the same on the current PHP4 release and the latest CVS PHP5
code.
Reproduce code:
---------------
<?php
function trap()
{
$tick = 0;
$x = array('x1'=>$tick, 'x2'=>$tick, 'x3'=>0,
'x4'=>0);
$y = array('y1'=>$tick, 'y2'=>$tick, 'y3'=>0,
'y4'=>0);
var_dump(get_defined_vars());
foreach ($x as $k => $v)
$$k =& $x[$k];
extract($y, EXTR_REFS);
var_dump(get_defined_vars());
$x1 = 1;
$y1 = 2;
$y3 = 4;
var_dump(get_defined_vars());
$tick = 5;
var_dump(get_defined_vars());
}
trap();
?>
Expected result:
----------------
Changing $y1 should only change it and y['y1'].
Changing $tick should only change $tick.
Actual result:
--------------
Changing $y1 or $tick changes the other as well.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=24630&edit=1