The SplObjectStorage class

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

Introduction

The SplObjectStorage class provides a map from objects to data or, by ignoring data, an object set. This dual purpose can be useful in many cases involving the need to uniquely identify objects.

Class synopsis

class SplObjectStorage implements Countable, SeekableIterator, Serializable, ArrayAccess {

/* Methods */

public function addAll(SplObjectStorage $storage): int

#[\Deprecated(
since: '8.5',
message: "use method SplObjectStorage::offsetSet() instead",
)]
public function attach(object $object, mixed $info = null): void

#[\Deprecated(
since: '8.5',
message: "use method SplObjectStorage::offsetExists() instead",
)]
public function contains(object $object): bool

public function count(int $mode = COUNT_NORMAL): int

public function current(): object

#[\Deprecated(
since: '8.5',
message: "use method SplObjectStorage::offsetUnset() instead",
)]
public function detach(object $object): void

public function getHash(object $object): string

public function getInfo(): mixed

public function key(): int

public function next(): void

public function offsetExists(object $object): bool

public function offsetGet(object $object): mixed

public function offsetSet(object $object, mixed $info = null): void

public function offsetUnset(object $object): void

public function removeAll(SplObjectStorage $storage): int

public function removeAllExcept(SplObjectStorage $storage): int

public function rewind(): void

public function seek(int $offset): void

public function serialize(): string

public function setInfo(mixed $info): void

public function unserialize(string $data): void

public function valid(): bool

}

Examples

Example #1 SplObjectStorage as a set

<?php
// As an object set
$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));
?>

The above example will output:

bool(true)
bool(true)
bool(false)
bool(true)
bool(false)
bool(false)

Example #2 SplObjectStorage as a map

<?php
// As a map from objects to data
$s = new SplObjectStorage();

$o1 = new stdClass;
$o2 = new stdClass;
$o3 = new stdClass;

$s[$o1] = "data for object 1";
$s[$o2] = array(1,2,3);

if (isset($s[$o2])) {
    var_dump($s[$o2]);
}
?>