ID: 27399
Updated by: [EMAIL PROTECTED]
Reported By: php dot bugs at darwin dot no-ip dot com
-Status: Open
+Status: Bogus
Bug Type: Scripting Engine problem
Operating System: Linux 2.4.18
PHP Version: 4.3.4
New Comment:
To get the expected result, change every "= new" to "=& new".
Previous Comments:
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[2004-02-25 16:39:02] php dot bugs at darwin dot no-ip dot com
Description:
------------
Copying an object doesn't appear to work as expected for either a
shallow or a deep copy.
Reproduce code:
---------------
class Dummy {}
$listA = new Dummy();
$listA->next = new Dummy();
$listA->next->previous =& $listA;
$listA->value = "one";
$listA->next->value = "two";
$listA->next->previous->value = "ONE";
echo "ListA: ";
echo "(" . $listA->value . ", " . $listA->next->value . ") \n";
$listB = $listA;
$listB->value = "three";
$listB->next->value = "four";
$listB->next->previous->value="THREE";
echo "(modified listB)\n";
echo "ListA: ";
echo "(" . $listA->value . ", " . $listA->next->value . ") \n";
echo "ListB: ";
echo "(" . $listB->value . ", " . $listB->next->value . ") \n";
Expected result:
----------------
Expected output: (ie: if PHP does a deep copy)
ListA: (ONE, two)
(modified listB)
ListA: (ONE, two)
ListB: (three, four)
This should happen because $listB->next->previous is a copy of the
reference
to $listA. Modifying it should not modify ListA OR ListB.
Possible (wrong) output: (if PHP had done a shallow copy)
ListA: (ONE, two)
(modified listB)
ListA: (THREE, four)
ListB: (three, four)
This would be the case because listB's next would be a reference to
ListA's
next.
Actual result:
--------------
Actual output:
ListA: (ONE, two)
(modified listB)
ListA: (THREE, two)
ListB: (three, four)
This looks like PHP did something between a shallow and a deep copy.
while ListB->next is a copy, ListB->next->previous still points at
ListA. (!?!)
... For an added bonus, try replacing '= new' with '=& new' and it
looks like
PHP does a shallow copy. From my reading of PHP documentation, I
thought PHP would always do deep (de-referencing) copies.
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Edit this bug report at http://bugs.php.net/?id=27399&edit=1
