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Date: Wed, 21 Apr 2021 17:59:39 +0200
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To: PHP Internals List <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] [Draft] Final constants
From: cschneid@cschneid.com (Christian Schneider)

Am 21.04.2021 um 17:08 schrieb Andreas Leathley <a.leathley@gmx.net>:
> On 21.04.21 15:14, Christian Schneider wrote:
>> I never really understood the desire to restrict how people can use
>> your code.
>> If there is no good reason to override the value of a class constant =
people won't do it.
>> If there might be a good reason (even one you as the original =
designer didn't predict) then why not leave that door open.
>>=20
>> While I understand the theoretical benefit of being able to specify =
this behavior I do think it is almost always counter productive and not =
a pattern I would encourage. Especially not in a dynamic language like =
PHP.
>=20
> Such restrictions also convey information and intent. One could argue
> defining a specific return type to a method is restricting its use, =
but
> it also clarifies how something should work and avoids unintended
> changes.

To me, the term 'constant' is good enough for that...

> final constants might be more niche, but it gives you a choice
> on how you want a class constant to behave if child classes are
> necessary and possibly done by someone else.

... but if child classes are necessary then how can you say that the =
constant's value should never be different for children?
Why not leave that to the user of your class? I've seen my share of =
damage done by assumptions about how code will be used later.

> Having "final" for constants seems a good addition to me, especially =
if
> the inconsistent behavior with interface constants can be solved at =
the
> same time.


Fixing this inconsistency should be discussed separately IMHO. Both =
because it is a side-effect and should not be used as a reason to add =
'final' as well as not fixing the problem for code *not* using 'final' =
with constants.

Side-note: Back in my Java days people argued with performance to add =
'final' but that only lead to it being sprinkled all over the place =
making code less flexible than it needed to be without real performance =
benefit. That's what I mean by promoting harmful patterns.

- Chris