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Date: Thu, 16 Apr 2020 13:00:24 +0200
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To: Nicolas Grekas <nicolas.grekas+php@gmail.com>
Cc: Enno Woortmann <enno.woortmann@web.de>, PHP Internals List <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Type hints in array destructuring expressions
From: michal.brzuchalski@gmail.com (=?UTF-8?Q?Micha=C5=82_Brzuchalski?=)

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Hi Nicolas,

czw., 16 kwi 2020 o 12:48 Nicolas Grekas <nicolas.grekas+php@gmail.com>
napisa=C5=82(a):

>
> > https://wiki.php.net/rfc/typehint_array_desctructuring
>>
>
> Thanks, Enno, I like it a lot!
> I hope the implementation won't find any blocker.
>
>
>
>> I fear that if you go that path people would automatically expect it to =
be
>> possible to write:
>>
>> int $id =3D $data['id'];
>> int $id =3D getIdFromData($data);
>>
>
> That would be a nice addition I guess - maybe for a separate RFC to keep
> the focus clear on this one.
>
>
>
>> And then expect the $id to behave more like typed property with type
>> guard.
>>
>
> I would not expect the type guard on my side, like function arguments
> don't provide type guards and also because this is PHP: runtime checks sl=
ow
> down the engine. Thus I would expect this to be guarded by static type
> analyzers for ppl who care (I'm not sure it matters personally, see SSA
> transformations), and on assignation otherwise to balance perf vs runtime
> overhead. (Note that the expectation you describe is a valid one, I'm jus=
t
> explaining that a different expectation exists, and why)
>
>
Agree this would slow things down but if it could be potentially type
checked on the assignment with type constraint in front of the variable
name I think that would be a neat feature.
So to work as a function parameter but not like a typed property.

Cheers,
Micha=C5=82 Brzuchalski

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