Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:80162
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: softfail (pb1.pair.com: domain tekwire.net does not designate 212.27.42.2 as permitted sender)
Reply-To: <francois@tekwire.net>
To: <internals@lists.php.net>
Date: Mon, 5 Jan 2015 00:49:34 +0100
Message-ID: <002b01d02879$17ce3c10$476ab430$@tekwire.net>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Thread-Index: AdAoeRd4uB/HgSApRZq7KNoH2L5Nbw==
Content-Language: fr
Subject: Friend classes revived
From: francois@tekwire.net (=?iso-8859-1?Q?Fran=E7ois_Laupretre?=)

Hi,

I know the subject was discussed years ago, and it was decided not to
implement 'friend class' declarations (see
https://bugs.php.net/bug.php?id=3D34044).

But the discussions occurred ten years ago, and things (and people) may =
be
different now.=20

Unfortunately, there is no easy-to-use and fast solution for this yet. =
Most
projects have asked for such a feature for years but, till now, they =
still
have to rely on a big warning in the documentation. Some, like symfony, =
also
add an '@internal' tag in their phpdoc block. This can be checked in an =
IDE
but that's information, not access restriction.

IMHO, such a feature would be a valuable addition for PHP 7. If you =
agree, I
will write an RFC.

The feature I was thinking about would be globally similar to C++ friend
classes, except that a PHP friend class would have access to protected
resources, but not private ones (private would remain private).

The inheritance rules would be similar to C++ rules (adapted from =
Wikipedia
as it originally includes access to private resources) :

* Friendships are not symmetric =96 If class A is a friend of class B, =
class B
is not automatically a friend of class A.

* Friendships are not transitive =96 If class A is a friend of class B, =
and
class B is a friend of class C, class A is not automatically a friend of
class C.

* Friendships are not inherited =96 A friend of class Base is not
automatically a friend of class Derived and vice versa; equally if Base =
is a
friend of another class, Derived is not automatically a friend and vice
versa.

* Access due to friendship is inherited =96 A friend of Derived can =
access the
protected members of Derived that were inherited from Base (simpler than =
the
C++ rule as friend classes and derived classes have the same access =
rights).

Another idea would be to base access restriction on namespaces, but, =
IMO,
namespaces would not bring the precision we need : each class needs to
define which classes are accepted as 'friends'.

Please comment.

Regards,

Fran=E7ois