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Date: Thu, 7 May 2020 01:10:42 -0700
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To: Benjamin Eberlei <kontakt@beberlei.de>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] <<Deprecated>> Attribute
From: davey@php.net (Davey Shafik)

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On Thu, May 7, 2020 at 00:22 Benjamin Eberlei <kontakt@beberlei.de> wrote:

> Hi everyone,
>
> The attributes RFC specifically looked into the use of attributes at the
> engine/compiler level.
>
> To have a showcase of this with the 8.0 release I want to propose this RF=
C
> for a <<Deprecated>> attribute:
>
> https://wiki.php.net/rfc/deprecated_attribute
>
> <<Deprecated>> is the most obvious engine attribute to add at the beginni=
ng
> in my opinion, as
>
> - all other languages with Attributes/Annotations support have it as well
> - its effects are quite obvious to understand, as such offer a good examp=
le
> and intro to attributes
> - with potential property/class constant deprecation it adds something th=
at
> was not possible in userland before.
>
> Let me know what you think!
>
> greetings
> Benjamin


Hi Benjamin,

Two things:

1) as a matter of course, I prefer things that can be done in userland be
done in userland unless there is a clear performance or other win. This
doesn't qualify for me, except that it would be possible to use the same
mechanism in core, but that really only gives us the ability to reason
around depredations with reflection and I don't see much value in that. I'm
not entirely convinced that a PSR and a defecto implementation isn't a
better solution here. This isn't a show-stopper though.

2) AFAICT you cannot add an attribute to a function argument, and the only
way I can see to resolve that is to add a "DeprecatedArgument" attribute
applied to the function that takes the name as the first arg (and the
message as the second). Now you're looking at:

<<DeprecatedArgument('foo')>>
<<DeprecatedArgument('bar')>>
function bat($foo =3D null, $bar =3D null) { }

It's not great IMO. Having said that, I don't think this bit is really
necessary =E2=80=94 unlike the other suggested uses, an argument isn't an i=
solated
thing, so much as part of the function signature as a whole and removing
arguments is better done by deprecating the entire function and introducing
a new version with a different name. So maybe we just don't need this?

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