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Date: Tue, 16 Nov 2021 23:46:52 +0100
To: internals@lists.php.net, Kamil Tekiela <tekiela246@gmail.com>,
 Dusk <dusk@woofle.net>
CC: PHP internals <internals@lists.php.net>
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Subject: =?US-ASCII?Q?Re=3A_=5BPHP-DEV=5D_Is_there_an_RFC/discuss?= =?US-ASCII?Q?ion_for_=3A=3Aclass_being_a_specific_type=3F?=
From: mel@dafert.at (Mel Dafert)

On 16 November 2021 23:02:59 CET, Kamil Tekiela <tekiela246@gmail=2Ecom> wr=
ote:
>Hi Dusk,
>
>Perhaps, you misunderstood me=2E Take a look at the documentation
>https://www=2Ephp=2Enet/manual/en/language=2Eoop5=2Ebasic=2Ephp#language=
=2Eoop5=2Ebasic=2Eclass=2Eclass
>::class is just a compile time transformation=2E It will give you the ful=
ly
>qualified name of *something* as a string literal=2E The only exception t=
o
>this is when using ::class on objects, as this is a runtime transformatio=
n,
>and when using with keyword static=2E
>
>When ::class is used with a class name, it will give you the name of that
>class as a string=2E When used with a name of a function, it will give yo=
u
>the name of that function as a string=2E When used with a string, it will
>give you that string as a string=2E
>See this example https://3v4l=2Eorg/EKnEd
>
>The fact that this gives you a callable is just coincidental with all
>strings being callable in PHP=2E The reason why it works right now is
>because a string can represent a name of a class, interface, trait or
>function=2E
>If we were to replace the transformation with something else, like it is
>proposed here, we would have to ensure that it is as versatile as a plain
>string=2E Otherwise we would be losing functionality=2E

In my opinion, this is extremely unintuitive and surprising=2E
I would not have expected this to work, and would consider this more of an
unintended side effect rather than an actual feature of ::class=2E

In my opinion, this is an argument for ::class producing a ClassName type,=
=20
and for migrating such code that misuses it for functions to the first-cla=
ss callable
syntax (ie=2E strlen(=2E=2E=2E))=2E
It might be even possible to issue a deprecation warning whenever a
ClassName is coerced to a callable - I am not sure how feasible it would b=
e to
implement this, however=2E