Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:30394
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 72.14.204.234 as permitted sender)
DomainKey-Status: bad
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=beta;
        h=received:from:to:cc:references:in-reply-to:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:thread-index:content-language;
        b=XOZUpZ5/YONKMuqDPKMkgZJ7xOUwxDfJNuJfmKZFffOENbcBfxcdjCqoTvb40oyAxUG594qIIaTSS9du8BGPgmrnKl07ymY6lYo2BNE8IRvUoBo2ZE+Dwha7eUJ3xfXyGGTPxM6iAWJKdj//cwGzUmaBGdPM6BiV3J3J1Z0JLPA=
To: "'Pavel Shevaev'" <pacha.shevaev@gmail.com>,
	"'Sebastian Bergmann'" <sb@sebastian-bergmann.de>
Cc: <internals@lists.php.net>
References: <468519DC.8060502@widescreen.ch> <4685785E.5010709@zend.com>	 <d9c3f61a0707010024l7f5c71f3r574bba46e51018f7@mail.gmail.com>	 <f67nh2$gg1$1@sea.gmane.org>	 <d9c3f61a0707010442l62be4d34ra0999447d02b3176@mail.gmail.com>	 <585221804.20070701154538@marcus-boerger.de>	 <d9c3f61a0707011218l51b56c86j8d76bdb61f4fe2db@mail.gmail.com>	 <f690hc$ti5$1@sea.gmane.org> <d9c3f61a0707011301n43d2591m9ed5b7b0fa3ae5a2@mail.gmail.com>
In-Reply-To: <d9c3f61a0707011301n43d2591m9ed5b7b0fa3ae5a2@mail.gmail.com>
Date: Sun, 1 Jul 2007 14:40:56 -0700
Message-ID: <002701c7bc28$8279c2c0$876d4840$@com>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit
Thread-Index: Ace8HvZDEPYKeJ/rSNG32ICQrp1ZTQACYBAA
Content-Language: en-us
Subject: RE: [PHP-DEV] toString() and Object #ID
From: planetbeing@gmail.com ("David")

(accidentally didn't send this to the whole group at first)

> Am I right in my guess that there's only a counter for each object 
> type? Still being not really unique this information could be very 
> useful and enough in many situations.

The "counter" is global, but it's not really a counter. "Object ids" are
actually handles (basically indices) into an internal array holding data to
all objects currently in memory. Handles are reused when an object is
destroyed so that the array could be kept as small as possible. However, if
you are comparing the handles of two objects that are known to be currently
in memory, if they have the same handle, then they are the same object (i.e.
one spot in memory).

However, if you stored the handle of the object in another area of memory so
that you can check it against other objects later, it's hard to ensure that
the results of that comparison is meaningful. Therefore, it's better to use
spl_object_hash to actually ensure objects are the same. Internally, the
hash is performed on the object handle (what you've been calling the "object
id") as well as the internal list of handlers for that object (basically the
"type" of the object), so there's reasonable confidence that a unique hash
will be generated. It looks like it's independent of the actual properties,
etc. of the object. Spl_object_hash is what you guys want.

David