SplObjectStorage::detach

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

SplObjectStorage::detach — オブジェクトをストレージから取り除く

説明

public SplObjectStorage::detach(object $object): void

オブジェクトをストレージから取り除きます。

パラメータ

object: 取り除きたいオブジェクト。

戻り値

値を返しません。

例

例1 SplObjectStorage::detach() の例

<?php
$o = new stdClass;
$s = new SplObjectStorage();
$s->attach($o);
var_dump(count($s));
$s->detach($o);
var_dump(count($s));
?>

上の例の出力は、たとえば以下のようになります。

int(1)
int(0)

参考

SplObjectStorage::attach() - オブジェクトをストレージに追加する
SplObjectStorage::removeAll() - 別のストレージに含まれているオブジェクトを現在のストレージから取り除く

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User Contributed Notes 4 notes

down

r dot wilczek at web-appz dot de ¶

14 years ago

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.

down

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

down

nawa ¶

2 years 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)
?>

down

Hayley Watson ¶

7 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));

?>

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