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Date: Wed, 30 Oct 2024 09:01:30 +0100
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
Subject: Re: [PHP-DEV] RFC: Support Closures in constant expressions
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

Am 2024-10-30 05:25, schrieb Larry Garfield:
> This seems like a good idea to me.  My only real question is why we 
> need to forbid short-closures.  I fully agree that capturing variables 
> for such functions doesn't work.  What I don't understand is why that 
> precludes short-closures.  Is it not possible to "just" say "there's 
> nothing to even capture in this context, don't try"?  (There may be 
> technical reasons for that, but I do not know what they are and the RFC 
> doesn't say.)

It would indeed require some special handling to disable the 
auto-capturing in the code. This would be solvable of course, but 
there's also semantic ambiguity, because users reasonably expect short 
closures to perform auto-capturing:

     <?php

     $foo = 'foo';

     const Closure = static fn (array $bar): array => [$foo, $bar];

     var_dump((Closure)('bar'));

If this would be legal syntax: What would you expect to be printed?

Best regards
Tim Düsterhus