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Date: Sun, 28 Jun 2020 14:33:55 +0200
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To: Stephen Reay <php-lists@koalephant.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Trait constants
From: nikita.ppv@gmail.com (Nikita Popov)

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On Sat, Jun 27, 2020 at 3:53 PM Stephen Reay <php-lists@koalephant.com>
wrote:

> Hi,
>
> It=E2=80=99s always struck me as slightly odd that traits don=E2=80=99t s=
upport constants
> the way classes and interfaces do.
> I tried to find an explanation of the lack of support in the original RFC=
,
> and came up empty.
>
> A consequent discussion in R11 has led me here.
> Can anyone working on internals explain why traits don=E2=80=99t allow co=
nstants
> (either technically or philosophically)?
> Moreover, what=E2=80=99s the opinion(s) of the list, on adding support fo=
r this?
> Would an RFC be needed?
>

Sounds like a reasonable addition. An RFC will be needed to specify the
details, which tend to be tricky whenever traits are involved. Some
suggestions:

 * Constants mustn't be accessible directly on the trait, i.e.
TraitName::FOOBAR throws. self::FOOBAR within the trait is legal in that
"self" is remapped to the using class, as usual.
 * The same constants important from multiple traits should follow the
rules of properties, i.e. require that values match. Conflict resolution
for constants should very much *not* be supported.

Regards,
Nikita

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