(PHP 5 >= 5.1.0, PHP 7, PHP 8)
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.
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]);
}
?>The above example will output:
array(3) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
int(3)
}