Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:123778
Content-Type: text/plain;
	charset=utf-8
Precedence: bulk
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.600.62\))
Subject: Re: [PHP-DEV] [RFC] Static class
In-Reply-To: <eb3f59cc-3ed8-461a-a3a4-f6ba10ed31e1@scriptfusion.com>
Date: Mon, 24 Jun 2024 10:27:12 +0200
Cc: php internals <internals@lists.php.net>
Content-Transfer-Encoding: quoted-printable
Message-ID: <88D83E92-94BE-4548-B398-8F5C74765FFD@gmail.com>
References: <eb3f59cc-3ed8-461a-a3a4-f6ba10ed31e1@scriptfusion.com>
To: Bilge <bilge@scriptfusion.com>
From: claude.pache@gmail.com (Claude Pache)


> Le 24 juin 2024 =C3=A0 01:10, Bilge <bilge@scriptfusion.com> a =C3=A9cri=
t :
>=20
> Hi Internals!
>=20
> I am pleased to present my first RFC: Static class =
<https://wiki.php.net/rfc/static_class>.
>=20
> This work is based on the previous discussion thread on this list of =
the same name, and hopefully captured all the relevant details, =
notwithstanding anything unanticipated that may present itself during =
the implementation. Let me know if you feel anything important has been =
missed. I am aware it omits to mention specifics about messages so =
emitted when runtime or compile-time errors occur, but I anticipate this =
can be hashed out in the PR, unless consensus indicates otherwise.
>=20
> I am aware this idea is not supported by everyone, but there seemed to =
be enough positive voices for it to be worth a shot. I'd like to get a =
better idea of where people might stand when it comes down to a vote, =
now there is a formal RFC, so we know whether it's worth completing the =
implementation, although any sentiments so proffered are of course not a =
commitment to vote any particular way and nobody should feel compelled =
to speak to that unless comfortable. Looking forward to feedback!
>=20
> Cheers,
> Bilge


Hi,

A general remark: I appreciate that a static class does not impose =
arbitrary restrictions (like: implicitly `final`) on the class beyond =
what is meaningful for staticness. On the other side, I don=E2=80=99t =
think that we should support markers that are technically possible, but =
semantically meaningless, like the `readonly` marker on class.

-----

Some more specific remarks:

* In the intro: =E2=80=9CA static class is a class whose members =
(properties and methods) are all static=E2=80=9D. One of the most =
important point is missing, namely: It is meaningless for a static class =
to have instances.

* In the =E2=80=9CProposal=E2=80=9D section, it should be stated =
explicitly that any attempt to construct an instance, not only with =
`new`, but also with any of the `ReflectionClass::newInstance*()` =
methods, or with `unserialize()`, or with whatever other mean, shall =
fail.

-----

Should a static class be marked `readonly` or `abstract`? I think not, =
because those have no real semantic meaning for static class; their =
effects on static members are only consequences of their intended =
meaning on non-static class:

* Unless/until the `readonly` marker may be applied to static =
properties, the only effect of such a keyword, is that it would prevent =
the creation of static properties. I don=E2=80=99t know if that =
restriction is useful, but in case it would be used for that purpose, it =
would be hijacking the `readonly` marker for a something it wasn=E2=80=99t=
 intended for.

* The main purpose of the `abstract` keyword is to prevent a class to be =
instantiated, which (in case of static class) is more semantically =
described by the `static` marker. Beyond that, it just allows to declare =
a method that, if implemented by a subclass, should have a compatible =
signature. Most notably, it does not prevent the other static members of =
the class to be used directly.

----

The RFC says that a static class may extend a class not explicitly =
marked as static, but with no instance member. This is not sound, =
because a class with no instance members is not necessarily static. The =
most obvious example is `stdClass` (which has no member at all, even if =
their instances may have properties).

=E2=80=94Claude