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Date: Mon, 12 Aug 2019 10:17:05 +0200
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To: Nikita Popov <nikita.ppv@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Namespace-scoped declares, again
From: nicolas.grekas+php@gmail.com (Nicolas Grekas)

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Le lun. 11 d=C3=A9c. 2017 =C3=A0 14:44, Nikita Popov <nikita.ppv@gmail.com>=
 a =C3=A9crit :

> Some time ago I introduced the following proposal for namespace-scoped
> declares:
>
>     https://wiki.php.net/rfc/namespace_scoped_declares
>
> The idea is to allow specifying declare directives for a whole library or
> project using:
>
>     namespace_declare('Vendor\Lib', ['strict_types' =3D> 1]);
>
> I've finally gotten around to implementing this proposal (
> https://github.com/php/php-src/pull/2972) and would like to move forward
> with it.
>
> The reason why I'm picking it up again is some feedback I received for th=
e
> explicit call-time send-by-ref proposal. The main objection seems to be
> that the feature has limited usefulness if it's optional rather than
> required, because you still can't be sure that something is a by-value
> pass, just because no & is present. At the same time, we can't make this
> required anytime soon due to the large BC impact.
>
> Namespace-scoped declares are perfectly suited to resolve this problem. W=
e
> can introduce a require_explicit_send_by_ref declare directive to make th=
e
> call-site annotation required, and libraries/projects can easily opt-in t=
o
> it using namespace_declare(). There would be no BC impact, while at the
> same time projects could benefit from the additional clarity and
> performance improvements immediately.
>

I've read discussions about the notion of a "package" and the way we should
define its boundaries.
What about the following?

Individual files could declare their package using this style:
<?php declare(package=3DMyVendor\MyPackage);

That would be enough to group a set of files together and make them share
eg some private classes, some optional PHP behaviors, etc.

The right side "MyVendor\MyPackage" would also be a FQCN that PHP would
autoload as a regular class. The corresponding class would then be the
place where ppl would declare the engine behavior they want for their
package (strict types, etc). To enforce this, the engine could require that
the "MyPackage" class implements some interface/extend some base abstract
class.

Of course, one could hijack a package and declare an unrelated file as part
of it, but I don't think that's an issue: the situation is the same as for
namespaces, where one can hijack a third party vendor namespace. In
practice, it proved not being an issue, and the original author's intent is
clear: "this is my namespace/package, if you mess with it, fine, but you're
on your own".

Nicolas

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