Detaching the current entry from the storage prevents SplObjectStorage::next() to operate.
Example as a PHPUnit-test:
<?php
public function testDetachingCurrentPreventsNext()
{
$storage = new SplObjectStorage;
$storage->attach(new stdClass);
$storage->attach(new stdClass);
$storage->rewind();
$iterated = 0;
$expected = $storage->count();
while ($storage->valid()) {
$iterated++;
$storage->detach($storage->current());
$storage->next();
}
$this->assertEquals($expected, $iterated);
}
?>
This test will fail, for the iteration will never reach the second stdClass.
SplObjectStorage::next() obviously relies on the current element to be valid.
If you want to detach objects during iterations, you should dereference objects, before you call next() and detach the reference after next():
<?php
public function testDetachingReferenceAfterNext()
{
$storage = new SplObjectStorage;
$storage->attach(new stdClass);
$storage->attach(new stdClass);
$storage->rewind();
$iterated = 0;
$expected = $storage->count();
while ($storage->valid()) {
$iterated++;
$object = $storage->current();
$storage->next();
$storage->detach($object);
}
$this->assertEquals($expected, $iterated);
}
?>
This test will pass.
SplObjectStorage::detach
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
SplObjectStorage::detach — Removes an object from the storage
Description
Removes the object from the storage.
Return Values
No value is returned.
Examples
Example #1 SplObjectStorage::detach() example
<?php
$o = new stdClass;
$s = new SplObjectStorage();
$s->attach($o);
var_dump(count($s));
$s->detach($o);
var_dump(count($s));
?>The above example will output something similar to:
int(1) int(0)
See Also
- SplObjectStorage::attach() - Adds an object in the storage
- SplObjectStorage::removeAll() - Removes objects contained in another storage from the current storage
add a note
User Contributed Notes 4 notes
r dot wilczek at web-appz dot de ¶
14 years ago
alan dot bem at gmail dot com ¶
11 years ago
SplObjectSotage::detach() has a bug - it rewinds internal array pointer.
Remember that - when looping over the storage - as it has no workaround.
https://bugs.php.net/bug.php?id=65629&edit=2
nawa ¶
1 year ago
There was problematic case when detaching object inside loop, because SplObjectStorage need to call next() before detach()
Example using foreach :
<?php
/**
* spl object storage bugs when looping
* @see https://bugs.php.net/bug.php?id=65629
*/
$firstStorage = new SplObjectStorage();
$secondStorage = new SplObjectStorage();
// temporary storage
$temporaryStorage = new SplObjectStorage();
// range 0 - 9
$range = range(0, 9);
foreach ($range as $id) {
$object = new stdClass();
$object->id = $id;
$firstStorage->attach($object);
$secondStorage->attach($object);
}
// direct detach inside loop
foreach ($firstStorage as $storage) {
// on common array it will detach all even in loop
// but object storage still remain 1 object
if ($storage->id < 5) {
$firstStorage->detach($storage);
}
}
// collect storage into temporary splObjectStorage
foreach ($secondStorage as $storage) {
// collect into temporary storage
if ($storage->id < 5) {
$temporaryStorage->attach($storage);
}
}
// removeAll by temporary Storage
$secondStorage->removeAll($temporaryStorage);
var_dump(count($firstStorage)); // int(6)
var_dump(count($secondStorage)); // int(5)
?>
Example using while :
<?php
$firstStorage = new SplObjectStorage();
$secondStorage = new SplObjectStorage();
// temporary storage
$temporaryStorage = new SplObjectStorage();
// range 0 - 9
$range = range(0, 9);
foreach ($range as $id) {
$object = new stdClass();
$object->id = $id;
$firstStorage->attach($object);
$secondStorage->attach($object);
}
$firstStorage->rewind();
while ($firstStorage->valid() && ($current = $firstStorage->current())) {
if ($current->id < 5) {
$firstStorage->detach($current);
}
// don't call next after detach
$firstStorage->next();
}
$secondStorage->rewind();
while ($secondStorage->valid() && ($current = $secondStorage->current())) {
// call next behavior before detach
$secondStorage->next();
if ($current->id < 5) {
$secondStorage->detach($current);
}
}
var_dump(count($firstStorage)); // int(6)
var_dump(count($secondStorage)); // int(5)
?>
Hayley Watson ¶
6 years ago
No complaints from SplObjectStorage if you try to detach an object that isn't in the collection; it's a no-op.
<?php
$o = new StdClass;
$t = new StdClass;
$s = new SplObjectStorage();
$s->attach($o);
var_dump(count($s));
$s->detach($t); // Didn't attach this one.
var_dump(count($s));
?>
