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In-Reply-To: <alpine.DEB.2.20.1508021808550.13034@whisky.home.derickrethans.nl>
Date: Sun, 2 Aug 2015 19:46:12 +0200
CC: Julien Pauli <jpauli@php.net>,
 PHP Internals <internals@lists.php.net>
References: <CAMUwpuTRzQHqznqKF-q=1Wy-Xnob9mra748E26YiZMKUa7-4DQ@mail.gmail.com> <alpine.DEB.2.20.1508021808550.13034@whisky.home.derickrethans.nl>
To: Derick Rethans <derick@php.net>
Subject: Re: [PHP-DEV] Exposing object handles to userland
From: bobwei9@hotmail.com (Bob Weinand)

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> Am 02.08.2015 um 19:09 schrieb Derick Rethans <derick@php.net>:
>=20
> On Fri, 31 Jul 2015, Julien Pauli wrote:
>=20
>> Hi people.
>>=20
>> I've been pinged many times to add a new spl_object_id() function to =
PHP,
>> that would return the internal object handle of an object.
>>=20
>> Today, spl_object_hash() partially allows that, but adds many =
randomness to
>> the result, which is not very cool to use later  (why does it even =
add
>> randomness ?).
>>=20
>> There has been topics about this subject.
>> For example, at =
http://marc.info/?l=3Dphp-internals&m=3D141814350920452&w=3D2
>>=20
>>=20
>> Beeing able to get the object handle back in PHP userland would ease =
many
>> tools, mainly debug-oriented tools.
>> I know PHPUnit, Symfony and many big projects today make use of
>> spl_object_hash() to identify objects.
>>=20
>> I also know people that print_r($an_object) and parse the output just =
to
>> extract the object handle from there... Crazy isn't it ?
>> Why couldn't we help those people by simply adding a new function =
that does
>> the job ?
>=20
> You realize that these object handles aren't particularly stable? The=20=

> same object ID can be reused:
>=20
> derick@whisky:/tmp $ cat objid.php=20
> <?php
> class Foo {}
> $a =3D new Foo;
> var_dump($a);
> $a =3D new Foo;
> var_dump($a);
> $a =3D new Foo;
> var_dump($a);
>=20
> derick@whisky:/tmp $ php objid.php=20
> class Foo#1 (0) {
> }
> class Foo#2 (0) {
> }
> class Foo#1 (0) {
> }
>=20
> You can't deterministically reference an object by it's class and=20
> handle... so I also think this implementation detail should not be=20
> shared through an API.
>=20
> cheers,
> Derick

Ehm, you realize that object id is only reset because the old object is =
freed? As long as the target object is referenced, nothing will have the =
same object id.

Which is why this isn't an issue. Is there any point in having an unique =
id? It's only 32 bit on some systems. When it once overflows, it'd be =
reused anyway.
What's important is having an exact 1:1 mapping of id and [existing] =
object. Which is all we need.

Bob=

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