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Date: Sat, 30 Nov 2019 21:29:32 +0000
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To: internals@lists.php.net
Message-ID: <05DFA426-3620-4A43-B48A-C6025F9EF24E@gmail.com>
Subject: Re: [PHP-DEV] Opt-in "use function *;" for skipping check for function/const in alternate namespace
From: rowan.collins@gmail.com (Rowan Tommins)

On 29 November 2019 19:48:37 GMT+00:00, Claude Pache <claude=2Epache@gmail=
=2Ecom> wrote:
>I don=E2=80=99t think it should be a declare() directive, because:
>
>* It changes incompatibly the meaning of valid (non-error-throwing)
>code=2E The current existing declare() directive,
>declare(strict_types=3D*), has the nice property that code that does not
>throw error in *both* modes does not change behaviour=2E
>
>* When you want to know the FQN of a random identifier, it is necessary
>and sufficient to look at the =E2=80=9Cnamespace=E2=80=9D and the =E2=80=
=9Cuse=E2=80=9D declarations=2E
>With `use function *`, that won=E2=80=99t change=2E With
>`declare(lookup_functions_somewhere)`, you have now to look at an
>additional place=2E


Hi Claude,

I understand both of these points, but both are subtly inaccurate=2E

1) strict_types is not the first or only declare directive=2E Declaring an=
 encoding fundamentally changes the meaning of a source file; probably it w=
ould be invalid in a different encoding, but errors are not the primary pur=
pose of the directive=2E Declaring a value of "ticks" actually changes the =
*runtime* behaviour of the code=2E The manual defines declare vaguely as "u=
sed to set execution directives", so it's not particularly clear to me that=
 changing namespace resolution would be outside of its purpose=2E

2) The existing fallback to global scope means that looking at the use sta=
tements of a file is not sufficient to resolve the ambiguity of an unprefix=
ed function name=2E Indeed, the same line of code can execute two different=
 functions within a running program if the namespaced function is defined a=
t the right time=2E

I'm generally not convinced that beginning the special directive with the =
word "use" automatically makes it easier to find or understand=2E Given som=
e code mentioning "strpos", you wouldn't be able to scan the list of use st=
atements for the word "strpos", you'd have to understand that there are two=
 modes of execution, and look for a line that switches between those modes=
=2E

I would expect that if it was worded as a use statement, coding standards =
would place it at the top of that list, so we're talking about the differen=
ce between:

declare(strict_types=3D1);
namespace Foo;
use global functions;
=2E=2E=2E

and

declare(strict_types=3D1);
declare(global_functions=3D1);
namespace Foo;
=2E=2E=2E


Regards,

--=20
Rowan Tommins
[IMSoP]