Класс SplObjectStorage
(PHP 5 >= 5.3.0)
Введение
Класс SplObjectStorage предоставляет соответствие объекты-данные или набор объектов, игнорируя данные. Эта двойная цель может быть полезна во многих случаях, включая необходимость уникальной идентификации объектов.
Обзор классов
/* Методы */
}Примеры
Пример #1 Класс SplObjectStorage как набор объектов
<?php
// Набор объектов
$s = new SplObjectStorage();
$o1 = new StdClass;
$o2 = new StdClass;
$o3 = new StdClass;
$s->attach($o1);
$s->attach($o2);
var_dump($s->contains($o1));
var_dump($s->contains($o2));
var_dump($s->contains($o3));
$s->detach($o2);
var_dump($s->contains($o1));
var_dump($s->contains($o2));
var_dump($s->contains($o3));
?>
Результат выполнения данного примера:
bool(true) bool(true) bool(false) bool(true) bool(false) bool(false)
Пример #2 Класс SplObjectStorage как отображение объектов в данные
<?php
// Как отображение объектов к данным
$s = new SplObjectStorage();
$o1 = new StdClass;
$o2 = new StdClass;
$o3 = new StdClass;
$s[$o1] = "данные для объекта 1";
$s[$o2] = array(1,2,3);
if (isset($s[$o2])) {
var_dump($s[$o2]);
}
?>
Результат выполнения данного примера:
array(3) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
int(3)
}
Содержание
- SplObjectStorage::addAll — Добавляет все объекты из другого контейнера
- SplObjectStorage::attach — Добавляет объект в контейнер
- SplObjectStorage::contains — Проверяет, содержит ли контейнер заданный объект
- SplObjectStorage::count — Возвращает количество объектов в контейнере
- SplObjectStorage::current — Возвращает текущий объект
- SplObjectStorage::detach — Удаляет объект object из контейнера
- SplObjectStorage::getHash — Вычисляет уникальный идентификатор для объектов контейнера
- SplObjectStorage::getInfo — Возвращает данные ассоциированные с текущим объектом
- SplObjectStorage::key — Возвращает индекс текущего положения итератора
- SplObjectStorage::next — Переход к следующему объекту
- SplObjectStorage::offsetExists — Проверяет, существует ли объект в контейнере
- SplObjectStorage::offsetGet — Возвращает данные ассоциированные с объектом object
- SplObjectStorage::offsetSet — Ассоциирует данные с объектом в контейнере
- SplObjectStorage::offsetUnset — Удаляет объект из контейнера
- SplObjectStorage::removeAll — Удаляет из текущего контейнера объекты, которые есть в другом контейнере
- SplObjectStorage::removeAllExcept — Удаляет из текущего контейнера все объекты, которых нет в другом контейнере
- SplObjectStorage::rewind — Переводит итератор на первый элемент контейнера
- SplObjectStorage::serialize — Сериализует контейнер
- SplObjectStorage::setInfo — Ассоциирует данные с текущим объектом контейнера
- SplObjectStorage::unserialize — Восстанавливает сериализованый контейнер из строки
- SplObjectStorage::valid — Определяет, допустимо ли текущее значение итератора
Коментарии
I have two things to note about SplObjectStorage:
#1: A reference to the object itself is stored (not just a hash to compare against the object) and it must be removed before the object is destroyed and the destructor is executed.
#2: SplObjectStorage::rewind() MUST be called to initiate the iterator and before SplObjectStorage::current() will return an object (and I think the only way to retrieve an object?) rather than automatically starting at the first element as I expected it to, like an array for example. This assumption is based on SplObjectStorage::current() returning NULL until SplObjectStorage::rewind() is called once the objects are contained. As a note, always use REWIND before iterating through or fetching objects.
<?php
class foo {
public function __destruct() {
print("--- DESTRUCTOR FIRED!!<br />\r\n");
}
}
# Create object and storage
$bar = new foo();
$s = new SplObjectStorage();
# Rewind early just as a test
$s->rewind();
# attach the object
$s->attach($bar, array('test'));
# Unset the object; destructor does NOT fire
unset($bar);
print("Object has been unset<br />\r\n");
# First demonstrate that REWIND must be called to initialize the iterator
$obj = $s->current();
var_dump($obj);
print("- Note the NULL (from \$s->current())<br />\r\n");
# Initialize, and then detach the current (and only) object
$s->rewind();
$s->detach( $s->current() );
# The destructor should NOW execute
?>
Output:
Object has been unset
NULL - Note the NULL (from $s->current())
--- DESTRUCTOR FIRED!!
I rewrote some scripts and changed object storage with arrays to SplObjectStorage. At some point I needed support of array_rand() but I did not find a function to return a random attached object of an SplObjectStorage object.
So here is my solution for random access to SplObjectStorage:
<?php
$o1 = new StdClass;
$o2 = new StdClass;
$s = new SplObjectStorage;
$s->attach($o1);
$s->attach($o2);
$random = rand(0,$s->count()-1);
$s->rewind();
for($i=0;$i<$random;$i++) {
$s->next();
}
var_dump($s->current());
?>
I needed to merge SplObjectStorages.
<?php
// As an object set
$SplObjectStorage_1 = new SplObjectStorage();
$object1 = new StdClass;
$object1->attr = 'obj 1';
$object2 = new StdClass;
$object2->attr = 'obj 2';
$object3 = new StdClass;
$object3->attr = 'obj 3';
$SplObjectStorage_1->attach($object1);
$SplObjectStorage_1->attach($object2);
$SplObjectStorage_1->attach($object3);
// Another one object set
$SplObjectStorage_2 = new SplObjectStorage();
$object4 = new StdClass;
$object4->attr = 'obj 4';
$object5 = new StdClass;
$object5->attr = 'obj 5';
$object6 = new StdClass;
$object6->attr = 'obj 6';
$SplObjectStorage_2->attach($object4);
$SplObjectStorage_2->attach($object5);
$SplObjectStorage_2->attach($object6);
/**
* Merge SplObjectStorage
*
* @param how many SplObjectStorage params as you want
* @return SplObjectStorage
*/
function mergeSplObjectStorage() {
$buffer = new SplObjectStorage();
if( func_num_args() > 0 ) {
$args = func_get_args();
foreach ($args as $objectStorage) {
foreach($objectStorage as $object) {
if(is_object( $object ) ) {
$buffer->attach($object);
}
}
}
}
else{
return FALSE;
}
return $buffer;
}
$merge = mergeSplObjectStorage($SplObjectStorage_1, $SplObjectStorage_2);
?>
<?php
echo $merge->count();
?>
Will output :
6
<?php
$merge->rewind();
while($merge->valid()) {
$object = $merge->current();
var_dump($object);
$merge->next();
}
?>
Will ouput :
object(stdClass)#2 (1) {
["attr"]=>
string(5) "obj 1"
}
object(stdClass)#3 (1) {
["attr"]=>
string(5) "obj 2"
}
object(stdClass)#4 (1) {
["attr"]=>
string(5) "obj 3"
}
object(stdClass)#6 (1) {
["attr"]=>
string(5) "obj 4"
}
object(stdClass)#7 (1) {
["attr"]=>
string(5) "obj 5"
}
object(stdClass)#8 (1) {
["attr"]=>
string(5) "obj 6"
}
My two cents.
Note some inconsistent/surprising behavior in SplObjectStorage to preserve backwards compatibility. You can't properly use foreach with key/value syntax.
<?php
$spl = new SplObjectStorage ();
$keyForA = new StdClass();
$keyForB = new StdClass();
$spl[$keyForA] = 'value a';
$spl[$keyForB] = 'value b';
foreach ($spl as $key => $value)
{
// $key is NOT an object, $value is!
// Must use standard array access to get strings.
echo $spl[$value] . "\n"; // prints "value a", then "value b"
}
// it may be clearer to use this form of foreach:
foreach ($spl as $key)
{
// $key is an object.
// Use standard array access to get values.
echo $spl[$key] . "\n"; // prints "value a", then "value b"
}
?>
See https://bugs.php.net/bug.php?id=49967
Do not use SplObjectStorage::detach when forach'ing over items in the storage as this skips the second (and only second) element.
Example:
<?php
class A {
public $i;
public function __construct($i) {
$this->i = $i;
}
}
$container = new \SplObjectStorage();
$container->attach(new A(1));
$container->attach(new A(2));
$container->attach(new A(3));
$container->attach(new A(4));
$container->attach(new A(5));
foreach ($container as $item) {
echo $item->i . "\n";
$container->detach($item);
}
echo "== Left in storage ==\n";
foreach ($container as $item) {
echo $item->i . "\n";
}
/* Outputs:
1
3
4
5
== Left in storage ==
2
*/
?>
Please note that SplObjectStorage has a Bug introduced with 5.4.0, breaking object lookup in cloned instances of derived classes that overwrite getHash().
This is a confirmed Bug: https://bugs.php.net/bug.php?id=67582
Example:
<?php
class MyObjectStorage extends SplObjectStorage {
// Overwrite getHash() with just some (working) test-method
public function getHash($object) { return get_class($object); }
}
class TestObject {}
$list = new MyObjectStorage(); // No issues if using "new SplObjectStorage()"
$list->attach(new TestObject());
foreach($list as $x) var_dump($list->offsetExists($x)); // TRUE
$list2 = clone $list;
foreach($list2 as $x) var_dump($list2->offsetExists($x)); // FALSE
?>
For anyone having issues with SplObjectStorages containing corrupt member variables after garbage collection (FatalErrorException after serializing): we used following fix to great effect
<?php
class FixedSplObjectStorage extends SplObjectStorage
{
public function serialize()
{
$goodPortion = 'N;;m:a:0:{}';
$startKey = 'N;;m:a:';
$serialized = parent::serialize();
$startPos = strpos($serialized, $startKey);
if ($startPos !== false) {
$serialized = substr_replace($serialized, $goodPortion, $startPos, -1);
}
return $serialized;
}
}
?>
Keep in mind that foreach() will copy your array before iterating, SplObjectStorage does not. If you have a sub call within an iteration that also calls foreach() on the object storage again, the iterator position collides!
To be safe use:
<?php
foreach(clone $myStorage as $obj) {
}
?>
if you're looking for a ResourceStorage, check https://gist.github.com/divinity76/b8041e073b74bdeab562a075fc94217f
(i needed it for socket programming with socket_select())
<?php
/**
* For simple use cases (where you want to keep objects in a map)
* I would suggest to stick to an plain old array. Just use the object
* hash as array key.
*/
$entity1 = new stdClass();
$entity2 = new stdClass();
$entities = [];
$entities[spl_object_hash($entity1)] = $entity1;
$entities[spl_object_hash($entity2)] = $entity2;
// object hashes are hard to distinguish so you could run a hash function
// on them for better readability.
$entities[md5(spl_object_hash($entity1))] = $entity1;
$entities[md5(spl_object_hash($entity2))] = $entity2;
print_r($entities);
SplObjectStorage class can be nicely used in Observer pattern, for example:
<?php
class Subject implements \SplSubject
{
private $observers;
public function __construct()
{
$this->observers = new \SplObjectStorage;
}
public function attach(\SplObserver $observer)
{
$this->observers->attach($observer);
}
public function detach(\SplObserver $observer)
{
$this->observers->detach($observer);
}
public function notify()
{
foreach ($this->observers as $observer) {
$observer->update($this);
}
}
}
?>
If you assign an array() to an object in SplObjectStorage and then try to modify its individual elements, you'll probably find it doesn't work.
Instead, you can use ArrayObject(), which will emulate array behaviour.
<?php
$storage = new SplObjectStorage();
$obj1 = new StdClass();
$obj2 = new StdClass();
$storage[$obj1] = array();
$storage[$obj2] = new ArrayObject();
$storage[$obj1]['person'] = 'Jana'; // Won't work (PHP Notice: Indirect modification of overloaded element of SplObjectStorage has no effect)
$storage[$obj2]['person'] = 'Jana'; // Works
var_dump($storage[$obj1]['person']); // NULL (PHP Notice: Undefined index: person)
var_dump($storage[$obj2]['person']); // string(4) "Jana"
?>