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ArrayObject> <spl_classes
Last updated: Fri, 14 Aug 2009

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spl_object_hash

(PHP 5 >= 5.2.0)

spl_object_hash Retourne l'identifiant de hashage pour un objet donné

Description

string spl_object_hash ( object $obj )

Cette fonction retourne un identifiant unique pour l'objet. Cet identifiant peut être utilisé comme clé de hashage pour stocker les objets ou pour les identifier.

Liste de paramètres

object

N'importe quel objet.

Valeurs de retour

Retourne une chaîne de caractères, unique pour chaque objet et qui est toujours la même pour le même objet.

Exemples

Exemple #1 Exemple avec spl_object_hash()

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



ArrayObject> <spl_classes
Last updated: Fri, 14 Aug 2009
 
add a note add a note User Contributed Notes
spl_object_hash
test user
14-Oct-2009 12:15
It is possible to mark objects with unique identity to establish required functionality:
<?php
if (!function_exists('spl_object_hash')) {
    function
spl_object_hash($object) {
        if (!
is_object($object)) {
           
trigger_error(__FUNCTION__ . "() expects parameter 1 to be object", E_USER_WARNING);
            return
null;
        }

        if (!isset(
$object->__oid__))
           
$object->__oid__ = uniqid();
        }
        return
$object->__oid__;
    }
}
?>
SlappyTheFish
28-May-2009 10:12
With regards to the previous post, I'm not entirely sure that easy does do it.   Consider the following code:

<?php

   
class Testy
   
{
        public
$something;

        public function
__toString()
        {
            return
serialize($this);
        }
    }

   
$objOne = new Testy();
   
$objOne->something = "hello";
   
   
$objTwo = new Testy();
   
$objTwo->something = "hello";

   
printf("objOne:\n");
   
printf("Bad way: %s\n", md5((string)$objOne));
   
printf("SPL Way: %s\n", spl_object_hash($objOne));   
   
   
printf("objTwo:\n");
   
printf("Bad way: %s\n", md5((string)$objTwo));
   
printf("SPL Way: %s\n", spl_object_hash($objTwo));
?>

The spl_object_hash function returns a hash based on the particular object, not the content.   The spl hash will always be the same for a given object, regardless of content.
andi.rein(AT)gmx de
15-Apr-2009 11:48
Easy does it

<?php
if (!function_exists('spl_object_hash')) {
   
/**
     * Returns the hash of the unique identifier for the object.
     *
     * @param object $object
     * @author Andreas Rein
     * @return string
     */
   
function spl_object_hash($object) {
        if (
is_object($object)) {
          return
md5((string)$object);
        }
       
trigger_error(__FUNCTION__ . "() expects parameter 1 to be object", E_USER_WARNING);
        return
null;
    }
}
?>
Rafael M. Salvioni
04-Dec-2008 07:01
The follow function is a implementation of the PHP´s function spl_object_hash(), unavailable in versions less 5.2.0.

But, the algorithm of this function is different of the original PHP´s function.

(Sorry... my english is very bad...)

<?php

if (!function_exists('spl_object_hash')) {
   
/**
     * Returns the hash of the unique identifier for the object.
     *
     * @param object $object Object
     * @author Rafael M. Salvioni
     * @return string
     */
   
function spl_object_hash($object)
    {
        if (
is_object($object)) {
           
ob_start(); var_dump($object); $dump = ob_get_contents(); ob_end_clean();
            if (
preg_match('/^object\(([a-z0-9_]+)\)\#(\d)+/i', $dump, $match)) {
                return
md5($match[1] . $match[2]);
            }
        }
       
trigger_error(__FUNCTION__ . "() expects parameter 1 to be object", E_USER_WARNING);
        return
null;
    }
}

?>
planetbeing
05-Jul-2007 11:40
Note that the contents (properties) of the object are NOT hashed by the function, merely its internal handle and handler table pointer. This is sufficient to guarantee that any two objects simultaneously co-residing in memory will have different hashes. Uniqueness is not guaranteed between objects that did not reside in memory simultaneously, for example:

var_dump(spl_object_hash(new stdClass()), spl_object_hash(new stdClass()));

Running this alone will usually generate the same hashes, since PHP reuses the internal handle for the first stdClass after it has been dereferenced and destroyed when it creates the second stdClass.

ArrayObject> <spl_classes
Last updated: Fri, 14 Aug 2009
 
 
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