Edit report at https://bugs.php.net/bug.php?id=52657&edit=1
ID: 52657 Comment by: maciej dot sz at gmail dot com Reported by: marco dot weber at uni-trier dot de Summary: create a spl_object_id function Status: Open Type: Feature/Change Request Package: SPL related Operating System: ANY PHP Version: Irrelevant Block user comment: N Private report: N New Comment: An implementation of this is avaliable, and can be compiled as an extension: http://stackoverflow.com/a/3089587/1697320 Previous Comments: ------------------------------------------------------------------------ [2012-11-15 14:55:08] maciej dot sz at gmail dot com @rasmus at mindplay dot dk: the thing is PHP already creates internal unique index for each instantiated object. The requested spl_object_id() function would only have to return it. You may have seen the value of this variable while debugging your scripts. Have you not noticed the overhead? ;) Just kidding. Anyway, your idea for workaround seemed reasonable to me, and now thanks to the traits in 5.4 I'm able to apply this unique object id to every class that I need. Just use the below trait. It is also immune to the __get/__set issue. The downside of this is that the id is a string containing class name. But if I'd need an id that is unique only within a specific class scope I can use integer value without the class name: <?php /** * Provides unique object's identifier. */ trait TObjectUniqueId { /** * Object's unique id. * * @var int */ protected $__oid__ = null; /** * @return string */ public function getObjectUniqueId() { static $__object_index = 1; if ( null === $this->__oid__ ) { $this->__oid__ = __CLASS__ . '\\' . $__object_index++; } return $this->__oid__; } } ------------------------------------------------------------------------ [2011-06-13 14:28:07] rasmus at mindplay dot dk I don't think attaching a serial number to every object from the get-go is a good approach, since this will add overhead (memory and CPU) for every object constructed. Objects are relatively lightweight in PHP, and sacrificing that for a feature that is probably less commonly used, to me, is unacceptable. What I would propose, is to assign a serial number the first time you access an object - something along the lines of this: public function object_serial($object) { static $next_sn = 1; if (!isset($object->__sn__)) $object->__sn__ = $next_sn++; return $object->__sn__; } You don't need to keep a serial-number in-memory until it's actually needed, and at that point, we'll just check and see if it already has an assigned serial- number. This is much simpler and easier on system-resources - the serial number is much lighter than the 32-character hash, and will work just as well. And since you're most likely going to use this value as index in an array, hash indexes will take up less memory, and lookups will probably be cheaper too. Unfortunately the PHP version of this collides with the magic __set() method, which is why the function shown above won't always work. If there were a way to go around the __get() and __set() methods, and directly access the properties of an object without colliding with these magic methods, that would probably be an even better solution. I would consider such a feature as belonging to the reflection domain - something like ReflectionObject::getValue($object, $name) and ReflectionObject::setValue($object, $name, $value) would do the trick. (this would probably have other uses too, so perhaps that's an even better solution to this problem, seeing as how implementing your own object_serial() method is literally only a few lines of code...) ------------------------------------------------------------------------ [2011-06-13 10:44:11] marco dot weber at uni-trier dot de i know, that there is nothing wrong with that method, as it does exactly, what the documentation says. Nevertheless, it would be great to have another function like spl_object_id(), that generates unique ids... Quotation from [2010-08-20 15:34 UTC] marco dot weber at uni-trier dot de : Since there is nothing wrong, with the spl_object_hash() method, i suggest to introduce a new spl_object_id() function. This could simply return an (internal) uint32, that is attached to every object on its creation. This counter gets incremented on every object that gets created. :) ------------------------------------------------------------------------ [2011-06-13 04:18:41] rasmus at mindplay dot dk I agree, this is a vital feature. Also, the description of spl_object_hash() in the documentation is highly misleading: "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." It does NOT always return a unique identifier, not even within a single running script. And it CANNOT be used as a key for storing objects, neither can it be used to identify an object. In fact, in the footnote, it basically says so: "When an object is destroyed, its hash may be reused for other objects." That fact precludes the uses mentioned in the first part of the documentation. I don't know what the intended use of that function is. It seems like it was an attempt to provide the functionality described in the first part of the documentation, because those are definitely things that could be put to good use in object-relational mappers, test-frameworks, etc... ------------------------------------------------------------------------ [2010-08-21 07:59:04] giorgio dot liscio at email dot it i've experienced problems with uniqueness ofspl_object_hash i think should be rebuilt with a better one algorithm there is no need (i think) of another function, just fix spl_object_hash i think it is really important to fix ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=52657 -- Edit this bug report at https://bugs.php.net/bug.php?id=52657&edit=1
