Return hash id for given object - Справочник: PHP5.4

string spl_object_hash ( object $obj )

This function returns a unique identifier for the object. This id can be used as a hash key for storing objects or for identifying an object.

A string that is unique for each currently existing object and is always the same for each object.

Пример #1 A spl_object_hash() example


<?php
$id = spl_object_hash($object);
$storage[$id] = $object;
?>

Замечание:
When an object is destroyed, its hash may be reused for other objects.