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Date: Wed, 30 Jan 2019 16:43:31 +0100
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To: Andreas Heigl <andreas@heigl.org>
Cc: Larry Garfield <larry@garfieldtech.com>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Old style constructors in PHP-8
From: nikita.ppv@gmail.com (Nikita Popov)

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On Wed, Jan 30, 2019 at 4:38 PM Andreas Heigl <andreas@heigl.org> wrote:

>
>
> Am Mittwoch, den 30.01.2019, 09:30 -0600 schrieb Larry Garfield:
> > On Wednesday, January 30, 2019 5:41:45 AM CST Nikita Popov wrote:
> > > On Wed, Jan 30, 2019 at 12:11 PM Dmitry Stogov <dmitry@zend.com>
> > > wrote:
> > > > Hi,
> > > >
> > > >
> > > > I've just noticed that Wordpress-4.1 on PHP master started
> > > > silently
> > > > produce different output.
> > > >
> > > > The problem that PHP master started to ignore old-style
> > > > constructors.
> > > >
> > > > They were deprecated in PHP-7 and PHP produced the following
> > > > warning
> > > >
> > > >
> > > > Deprecated: Methods with the same name as their class will not be
> > > > constructors in a future version of PHP; ... has a deprecated
> > > > constructor
> > > >
> > > >
> > > > PHP master doesn't produce any warnings and just constructs a
> > > > class
> > > > without constructor.
> > > >
> > > > This silent behavior change may become a problem for porting
> > > > legacy code
> > > > to PHP-8,
> > > >
> > > > May be, it makes sense to emit fatal error in case of old-style
> > > > constructor.
> > > >
> > > >
> > > > Thanks. Dmitry.
> > >
> > > First of all, it is probably important to note that the RFC for
> > > this (
> > > https://wiki.php.net/rfc/remove_php4_constructors) explicitly
> > > specifies
> > > that in PHP 8 methods with the same name as the class are
> > > interpreted as
> > > ordinary methods and no warning or error is thrown. I've CC'd Levi
> > > and
> > > Andrea, who authored this RFC.
> > >
> > > I think as an end goal, what the RFC specifies is preferable for a
> > > number
> > > of reasons:
> > >
> > >  * You should be able to call your methods whatever you like. PHP
> > > only
> > > reserves the __ prefix for itself.
> > >  * The behavior is consistent with classes inside namespaces, where
> > > methods
> > > with the same name as the class are treated as normal methods for a
> > > long
> > > time already.
> > >  * The fact that a method has the same name as the class may be
> > > completely
> > > incidental if it comes from a trait (see
> > > https://bugs.php.net/bug.php?id=77470). The trait does not control
> > > in which
> > > classes it may be used and which names those classes may have.
> >
> > Every Drupal 7 or 8 site includes classes that have a method name the
> > same as
> > the class name, on the assumption that it's safe to do for a normal
> > method in
> > current PHP versions.  Making that suddenly a Fatal would be, er,
> > bad. :-)
> >
> > As others have noted, this is easily solved with static analysis
> > tools.
> > There's been discussion of WP moving to a PHP 7-based version of PHP
> > sometime
> > this year (no promises, but that's the scuttlebutt), which would let
> > them
> > convert to __construct() universally and safely well before PHP 8
> > becomes an
> > issue.
>
> AFAIK WP requires PHP5 already as the minimum PHP-Version. And AFAIK
> __construct worked with that as well. So there should be no need to
> wait for PHP7 readiness in WordPress to tackle this issue.
>
> Replacing the function-name-as-class-name constructors with __construct
> should be possible without a BC-break already. Even with PHP 5.0 as a
> min-requirement.
>
> Or am I missing something?
>

That's correct. The standard pattern is to do something like this:

class Foobar {
    public function __construct($args) { ... }
    public function Foobar($args) { $this->__construct($args); }
}

This ensures BC even for cases where people are explicitly calling
Foobar::Foobar() for some reason (e.g. because they don't know that
parent::__construct() can be used even if the parent constructor is not
named __construct).

WordPress does use this pattern for their constructors. The original
problem that Dmitry ran into is that WordPress 4.1 was released one year
before PHP 7, so they obviously didn't do this constructor migration at
that point in time yet.

Nikita

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