ID: 39384 Comment by: s dot s at terra dot com dot br Reported By: cw264701 at ohiou dot edu Status: Open Bug Type: Class/Object related Operating System: Ubuntu Linux PHP Version: 5.2.0 New Comment:
The object still running as expected. If you change the attribute table, its sure that when you read it again the value will be the last assigned; null in this case. Try to eliminate the line "$this->table = null;" and run the test again. You dont need to set the attribute to null to serialize the object as you are doing. The magic method __sleep is used to persist only the attributes you whant, not the entire object ;) >From the docs: ----------------- serialize() checks if your class has a function with the magic name __sleep. If so, that function is executed prior to any serialization. It **can** clean up the object and is supposed to return an array with the names of all variables of that object that **should** be serialized. Previous Comments: ------------------------------------------------------------------------ [2006-11-04 20:59:46] cw264701 at ohiou dot edu Description: ------------ PHP assumes that I will not use an object after serializing it. This shouldn't cause problems if my object's class does not define a __sleep() function, but if it does, and that __sleep() function modifies the object, then I can't reliably use that object until it is recreated using unserialize(). There is no mention of this in the documentation for the serialize() function, or anywhere else that I saw. More importantly, if PHP expects me to *not* use an object after calling serialize() on it, then PHP should produce an error message if I *do* try to use that object before unserialization. This is one of several problems (not all necessarily "bugs", but shaky designs), that I've come across recently, which greatly reduces the ability for PHP applications to take advantage of *transparency*. I.e., I should not have to care how a class is implemented (for instance, whether or not it uses the magic __sleep() function) to make use of it. I recently adopted the ezpdo (http://ezpdo.net/) ORM tool. It has probably hurt my productivity more than it has helped because it makes use of such leaky abstractions. Some of these may be the fault of that tool, but many flaws like this seem to be more general PHP problems. (Sorry for the rant, but I think issues like this are pretty important, and the reason I very often become frustrated with PHP.) Reproduce code: --------------- <?php class MultiplicationTable { public $size; public $table; public function MultiplicationTable( $size ) { $this->size = $size; for( $a = 1; $a <= $size; ++$a ) { for( $b = 1; $b <= $size; ++$b ) { $this->table[$a][$b] = $a * $b; } } } public function __sleep() { $this->table = null; return( array("size") ); } public function __wakeup() { $this->MultiplicationTable($this->size); } } $mt = new MultiplicationTable(4); echo $mt->size . ", " . $mt->table[4][4] . "\n"; $serialized_mt = serialize($mt); echo $mt->size . ", " . $mt->table[4][4] . "\n"; $unserialized_mt = unserialize($serialized_mt); echo $unserialized_mt->size . ", " . $unserialized_mt->table[4][4] . "\n"; ?> Expected result: ---------------- Well, ideally the object would still "work" after creating a serialize()'d version of it, but I think making that work would require significant changes to PHP's whole serialization model (or perhaps you could just have __wakeup() be called right after serialization; perhaps only if the object is accessed again). But, the more realistic solution would probably result in some kind of error message when I try to access my $mt object after calling serialize() on it. Actual result: -------------- 4, 16 4, 4, 16 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=39384&edit=1
