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Subject: Re: [PHP-DEV] Module or Class Visibility, Season 2
In-Reply-To: <44F59416-3922-4AF4-881A-C64F2C4E9345@rwec.co.uk>
Date: Fri, 30 May 2025 20:21:08 +0200
Cc: PHP Internals <internals@lists.php.net>
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To: "Rowan Tommins [IMSoP]" <imsop.php@rwec.co.uk>
From: alwin@garsi.de (Alwin Garside)

On 30 May 2025, at 18:38, Rowan Tommins [IMSoP] <imsop.php@rwec.co.uk> =
wrote:
>=20
> On 30 May 2025 08:57:34 BST, Rob Landers <rob@bottled.codes> wrote:
>>=20
>> I=E2=80=99m starting to think that maybe modules might be a bad idea; =
or at least, class/module visibility.
>>=20
>> As an anecdote, I was looking to extract a protobuf encoding library =
from a larger codebase and create a separate library for Larry=E2=80=99s =
Serde library. During the extraction I realized that many of the classes =
and functions I was relying on actually used @internal =
classes/functions. If =E2=80=9Cmodule=E2=80=9D visibility were a =
thing=E2=80=A6 would my implementation have been possible?
>>=20
>> In other words, if visibility comes with modules; there really needs =
to be some kind of escape hatch. Some way to say, =E2=80=9CI know what =
I=E2=80=99m doing, so get out of my way.=E2=80=9D
>=20
>=20
> Isn't this exactly the same as any other "access control" feature?
>=20
> We have private/protected methods and properties, final methods and =
classes, readonly properties; other languages also have sealed classes, =
module and/or file private, etc. All of these are ways for the author of =
the code to express how they intend it to be used, and to protect users =
against *accidentally* violating assumptions the code is relying on.
>=20
> They are of course not *security* measures, as they can be bypassed =
via Reflection or just editing the source code.
>=20
> If you're using someone else's code in ways they didn't intend, that's =
up to you, but you may need to make changes to do so, i.e. fork it =
rather than relying on the distributed version.=20

If the goal is to hint consumers of a library about the (lack of) =
guarantees regarding a method or its signature, then perhaps an =
`#[\Internal]` attribute makes sense.

```php
namespace Acme\Foo;

class Foo
{
    #[\Internal('Acme')]
    public function bar() { /* ... */ }
}
```

In the example above, I image calling or extending the `Foo::bar()` =
method from somewhere outside the `Acme` namespace would trigger an =
E_USER_WARNING or E_USER_NOTICE. The warning/notice could then be =
suppressed when explicitly overriding an `#[\Internal]` method with =
`#[\Override]`.

Alwin=