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Date: Tue, 20 Apr 2021 02:25:51 +0800
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Subject: RE: [PHP-DEV] [RFC] [Draft] Final constants
From: me@jhdxr.com (=?utf-8?b?Q0hVIFpoYW93ZWk=?=)

Hi Mate,

Can I ask why you use late static binding while you don't want your =
constant value to be changed/overridden by child classes? IMHO, =
`self::FOO` is all you need.

Regards,
CHU Zhaowei

-----Original Message-----
From: M=C3=A1t=C3=A9 Kocsis <kocsismate90@gmail.com>=20
Sent: Sunday, April 18, 2021 10:20 PM
To: PHP Internals List <internals@lists.php.net>
Subject: [PHP-DEV] [RFC] [Draft] Final constants

Hi Internals,

I've recently realized that class constant values cannot always be =
trusted when late static binding is involved (e.g. static::FOO or =
$this::FOO), since they can be freely overridden in child classes. =
That's why the engine knows neither the type and the value before =
run-time.

Doctrine coding standards has a specific rule which disallows =
referencing a possibly overridden class constant (
https://github.com/doctrine/coding-standard/blob/8d75920bb04a9be4c73c2a77=
5ee5766262cf2a0d/lib/Doctrine/ruleset.xml#L123
),
but I'm wondering if it would be better to simply make it possible to =
allow declaring class constants final  (thus disallowing overriding) =
instead?

In my opinion, final constants would come with two advantages:
- make class constant declarations paranoidly safe
- allow the engine to optimize class constants references in LSB context

Although I admit that the win is not extra huge, I do think that it =
would still be useful to have this feature, especially considering that =
the implementation is very straightforward ( =
https://github.com/php/php-src/pull/6878). So that's why I'm proposing =
this as an RFC.

Recently, a similar attempt to make class constant declarations safer =
was the Typed Constants RFC =
(https://externals.io/message/110755#110755), but unfortunately it has =
halted since then. I think final and typed constants would be a nice =
little addition, and would complement each other well.

Regards,
M=C3=A1t=C3=A9