Bug #52157 [Com]: Unwanted call of the magic __get method
Edit report at http://bugs.php.net/bug.php?id=52157&edit=1
ID: 52157
Comment by: mail_ben_schmidt at yahoo dot com dot au
Reported by: l dot declercq at nuxwin dot com
Summary: Unwanted call of the magic __get method
Status: Open
Type: Bug
Package: Scripting Engine problem
Operating System: Debian
PHP Version: 5.2.14RC1
Block user comment: N
New Comment:
You are trying to do something not supported by PHP. The key is in your
final error: Cannot assign by reference to overloaded object.
The way assign-by-reference works is that it gets a reference to the
left-hand-side of the assignment, and then changes that to be a
reference to the right hand side. So it is no surprise that __get() is
called. However, PHP does not support returning a reference from __get()
and assigning to that reference. This feature would need to be added to
PHP for it to work, and it is not a simple task, because __get() needs
to be able to work for non-references; it would probably require a new
magic method for assign-by-reference, &__getReference($index) or
something like that.
I assume your intention is that it behave the same way as it would
behave if you did not have a __get() method. In this case, I suggest you
do an assignment by value (of anything!) and then assign by reference to
the now-existing property:
public static function &setAlias($index, &$value) {
$instance = self::getInstance();
// Create the property if it doesn't exist
if (!isset($instance->$index)) $instance->$index = true;
// Set it by reference
return $instance->$index = &$value;
}
Of course, this will only work if any __isset() method does what is
sensible, and any __set() method actually does create the member $index.
Previous Comments:
------------------------------------------------------------------------
[2010-06-23 18:07:16] l dot declercq at nuxwin dot com
oops, sorry, it's the magic __get() methods that is unwanted here, not
the magic __call() method ..
------------------------------------------------------------------------
[2010-06-23 12:43:45] l dot declercq at nuxwin dot com
Description:
------------
hello everyone ;
In the documentation, it's said that the magic __call method is called
when an inaccessible member is read. But I've small issue in my current
class with a setter method. When I try to set an Alias on an inexistent
member, the magic __call method is also called.
To solve the problem, I uses a workaround like this in the setter
method:
public static function &setAlias($index, &$value) {
$instance = self::getInstance();
// Small workaround to avoid call of magic __get().
$instance->$index = '';
return $instance->$index = &$value;
}
Strange behavior, no ? It's bug or not, if not, can you explain to me
the reason of this statement ? I uses php 5.2.6.
Sorry, for my poor english, I'm french.
Test script:
---------------
class Registry {
protected static $_instance = null;
public static function getInstance() {
if(self::$_instance == null) {
self::$_instance = new self;
}
return self::$_instance;
}
public function __get($index) {
print 'Oh my god...';
}
public static function &setAlias($index, &$value) {
$instance = self::getInstance();
return $instance->$index = &$value;
}
}
class myObject {
protected static $_instance = null;
public static function &getInstance() {
if(self::$_instance == null) {
self::$_instance = new self();
}
return self::$_instance;
}
}
// Here, I want register a myObject instance by reference (not by
object identifier)
Registry::setAlias('MyData', myObject::getInstance());
echo '<pre>';
var_dump(Registry::getInstance());
echo '</pre>';
Expected result:
----------------
object(Registry)#2 (1) {
["MyData"]=>
&object(myObject)#1 (0) {
}
}
Actual result:
--------------
Oh my god... Notice: Indirect modification of overloaded property
Registry::$MyData has no effect in /var/www/test.php on line 67 Fatal
error: Cannot assign by reference to overloaded object in
/var/www/test.php on line 67
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/bug.php?id=52157&edit=1
Thread (4 messages)