Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:97763
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 74.125.82.41 as permitted sender)
To: internals@lists.php.net
References: <0DE25BF8-D349-48EF-A83B-8837DD4AD1E0@gmail.com>
 <5efcc230-c67b-4439-cc82-b31eacbf36db@php.net>
 <CAOv67gsHZRBXugtknriqz4ofndsfaS2KBFjjMdahqKpCB8c+kA@mail.gmail.com>
 <7c8c8801-a849-6fd2-91e9-954030c55e83@fleshgrinder.com>
 <cc6bc980-29fd-2c6f-fc67-0de79c27409a@heigl.org>
 <2051639b-1b63-2e44-51b0-381caa54dfd0@fleshgrinder.com>
 <BC86F6B0-0B13-4DCA-9738-9019363953B2@heigl.org>
 <CAML1Pf7CobE=cf6MWi41oT+6vkg91fcvjwi0v937vpgDWVuvzw@mail.gmail.com>
Message-ID: <17bb5ec4-833d-d827-0932-390723d52665@gmail.com>
Date: Sun, 15 Jan 2017 17:34:55 +0000
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.6.0
MIME-Version: 1.0
In-Reply-To: <CAML1Pf7CobE=cf6MWi41oT+6vkg91fcvjwi0v937vpgDWVuvzw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] Explicit constructor call and polymorphic dispatch
From: rowan.collins@gmail.com (Rowan Collins)

On 14/01/2017 14:58, Giovanni Giacobbi wrote:
> If you go for blocking explicit calls to __construct() (i'm personally in
> favour of it), i hope you would change the syntax for its only legitimate
> use which is calling the parent's constructor within a constructor, so how
> about something like parent(...)?
> It would be ugly to say "You are not supposed to explicit call
> __construct() *ever*" and then "You know what, to initialize parent class
> you need to call __construct()".

This is actually a very good point: if you ban calls to __construct, you 
need syntax for not only calling the parent constructor, but other 
constructors in the chain. For instance [https://3v4l.org/jTsek]:

<?php

class A
{
     public function __construct() {
         echo 'A';
     }
}
class B extends A
{
     public function __construct() {
         parent::__construct();
         echo 'B';
     }
}
class C extends B
{
     public function __construct() {
         // Skip parent constructor, but call grand-parent
         A::__construct();
         echo 'C';
     }
}
new C;


Probably you could say "cannot call __construct directly, except in the 
__construct of a descendant class", but that all seems a bit fiddly.

I'm on the -1 side on this proposal, because the logical conclusion 
would be that all magic methods should be banned: __clone was already 
mentioned, but should you really be calling $foo->__get($bar) directly? 
If so, why is that more legitimate than $foo->__construct? And if not, 
do you allow parent::__get($bar), or do you insist on that using 
different syntax as well? (If you think the answers are easy for __get, 
pick a different magic method and ask the same questions).

These exceptions and special cases are going to proliferate, and all to 
stop a hypothetical "misuse" of the language. Do you have an example of 
a bug you've seen where a user acting reasonably would have been saved 
by this new prohibition?

Regards,

-- 
Rowan Collins
[IMSoP]