all,

i was playing around w/ some object serialization tonight during
further exploration of spl and i stumbled on what appears to be a
bug in the behavior of the __sleep() magic method.

here is the pertinent documentation on the method
..is supposed to return an array with the names of all variables
of that object that should be serialized.

so, the idea is, *only* the instance variables identified in the array
returned are marked for serialization.
however, it appears all instance variables are being serialized no matter what.
see the reproducible code below. ive run this on 2 separate php5
boxes, one w/ 5.2.5, another w/ a 5.2.something..

<?php
class A {
public $a1 = 'a1';
public $a2 = 'a2';
public $a3 = 'a3';

public function __sleep() {
echo __FUNCTION__ . PHP_EOL;
return array('a1', 'a2');
}
}

var_dump(unserialize(serialize(new A())));
?>

this is what i get despite having marked only member variables 'a',
and 'b' for serialization.

__sleep
object(A)#1 (3) {
["a1"]=>
string(2) "a1"
["a2"]=>
string(2) "a2"
["a3"]=>
string(2) "a3"
}

consensus ?

-nathan

On Jan 29, 8:52 pm, quickshif...@gmail.com ("Nathan Nobbe") wrote:
> all,
>
> i was playing around w/ some object serialization tonight during
> further exploration of spl and i stumbled on what appears to be a
> bug in the behavior of the __sleep() magic method.
>
> here is the pertinent documentation on the method
> ..is supposed to return an array with the names of all variables
> of that object that should be serialized.
>
> so, the idea is, *only* the instance variables identified in the array
> returned are marked for serialization.
> however, it appears all instance variables are being serialized no matter what.
> see the reproducible code below. ive run this on 2 separate php5
> boxes, one w/ 5.2.5, another w/ a 5.2.something..
>
> <?php
> class A {
> public $a1 = 'a1';
> public $a2 = 'a2';
> public $a3 = 'a3';
>
> public function __sleep() {
> echo __FUNCTION__ . PHP_EOL;
> return array('a1', 'a2');
> }
>
> }
>
> var_dump(unserialize(serialize(new A())));
> ?>
>
> this is what i get despite having marked only member variables 'a',
> and 'b' for serialization.
>
> __sleep
> object(A)#1 (3) {
> ["a1"]=>
> string(2) "a1"
> ["a2"]=>
> string(2) "a2"
> ["a3"]=>
> string(2) "a3"
>
> }
>
> consensus ?
>
> -nathan

When you unserialize it $a3 gets the default value you specified in
the class declaration. Try this:

$a = new A();
$a->a3 = 'foo';
var_dump($a);
var_dump(unserialize(serialize($a)));

See the difference?

Nathan Nobbe wrote:
> all,
>
> i was playing around w/ some object serialization tonight during
> further exploration of spl and i stumbled on what appears to be a
> bug in the behavior of the __sleep() magic method.
>
> here is the pertinent documentation on the method
> ..is supposed to return an array with the names of all variables
> of that object that should be serialized.
>
> so, the idea is, *only* the instance variables identified in the array
> returned are marked for serialization.
> however, it appears all instance variables are being serialized no matter what.
> see the reproducible code below. ive run this on 2 separate php5
> boxes, one w/ 5.2.5, another w/ a 5.2.something..
>
> <?php
> class A {
> public $a1 = 'a1';
> public $a2 = 'a2';
> public $a3 = 'a3';
>
> public function __sleep() {
> echo __FUNCTION__ . PHP_EOL;
> return array('a1', 'a2');
> }
> }
>
> var_dump(unserialize(serialize(new A())));
> ?>
>
> this is what i get despite having marked only member variables 'a',
> and 'b' for serialization.
>
> __sleep
> object(A)#1 (3) {
> ["a1"]=>
> string(2) "a1"
> ["a2"]=>
> string(2) "a2"
> ["a3"]=>
> string(2) "a3"
> }
>
> consensus ?
>

To check if __sleep is proper, you should be doing
var_dump(serialize(new A()));

unserialize'ing effectively also does a __wakeup()

This should give a clearer picture

<?php
class A {
public $a1 = 'a1';
public $a2 = 'a2';
public $a3 = null;

public function __construct(){
$this->a3 = 'a3';
}

public function __sleep() {
echo __FUNCTION__ . PHP_EOL;
return array('a1', 'a2');
}
}

var_dump(unserialize(serialize(new A())));
?>

__sleep
object(A)#1 (3) {
["a1"]=>
string(2) "a1"
["a2"]=>
string(2) "a2"
["a3"]=>
NULL
}

============= and ======================

<?php
class A {
public $a1 = 'a1';
public $a2 = 'a2';
public $a3 = null;

public function __construct(){
$this->a3 = 'a3';
}

public function __sleep() {
echo __FUNCTION__ . PHP_EOL;
return array('a1', 'a2', 'a3');
}
}

var_dump(unserialize(serialize(new A())));
?>

__sleep
object(A)#1 (3) {
["a1"]=>
string(2) "a1"
["a2"]=>
string(2) "a2"
["a3"]=>
string(2) "a3"
}

--
Regards,
Anup Shukla