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

    classSplObjectStorageimplementsCountable, Iterator, Serializable, ArrayAccess {
    publicaddAll(SplObjectStorage$storage): int
    publicattach(object$object, mixed$info = null): void
    publiccontains(object$object): bool
    publiccount(int$mode = COUNT_NORMAL): int
    publiccurrent(): object
    publicdetach(object$object): void
    publicgetHash(object$object): string
    publicgetInfo(): mixed
    publickey(): int
    publicnext(): void
    publicoffsetExists(object$object): bool
    publicoffsetGet(object$object): mixed
    publicoffsetSet(object$object, mixed$info = null): void
    publicoffsetUnset(object$object): void
    publicremoveAll(SplObjectStorage$storage): int
    publicremoveAllExcept(SplObjectStorage$storage): int
    publicrewind(): void
    publicserialize(): string
    publicsetInfo(mixed$info): void
    publicunserialize(string$data): void
    publicvalid(): 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]);
    }
    ?>

    The above example will output:

     array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }

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