Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:122984
Message-ID: <efe19f77-058f-48c4-aa33-fcc9223836ac@bastelstu.be>
Date: Fri, 5 Apr 2024 22:00:32 +0200
Precedence: bulk
MIME-Version: 1.0
Subject: Re: [PHP-DEV] [RFC] [Discussion] Support object type in BCMath
To: Saki Takamachi <saki@sakiot.com>, Jordan LeDoux <jordan.ledoux@gmail.com>
Cc: Lynn <kjarli@gmail.com>, Aleksander Machniak <alec@alec.pl>,
 php internals <internals@lists.php.net>
References: <CAMrTa2Geo1XHFxfa1Mj6tXcYC-gVwQeUK+Wk0h11d1fELUyZJQ@mail.gmail.com>
 <46B14427-44B2-4665-BC14-6018AC34B0CF@sakiot.com>
Content-Language: en-US
In-Reply-To: <46B14427-44B2-4665-BC14-6018AC34B0CF@sakiot.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

On 4/5/24 21:42, Saki Takamachi wrote:
> The only solution I can think of at the moment is to impose the constraint that
> when computing operator overloading, if the operands are both objects, they must
> be of the exact same class.

Even that would allow for confusing behavior:

     class MyNumber extends Number {
         private $importantMetadata;

         public function doSomething() {
             $this->importantMetadata = random_int(1, 100);
         }
     }

     $a = new MyNumber(5);
     $a->doSomething();
     $b = new MyNumber(10);
     $b->doSomething();

     $what = $a + $b;

What should be the value of $what->importantMetadata be? The property is 
private, so as a user adding two of MyNumber would not even be able to 
manually fix it up with the correct value, thus requiring the addition 
of a "fixup" method that fixes the internal state of the object, 
possibly even lacking the necessary information to properly fix up the 
state, because it does not know which operations lead to the state.

Best regards
Tim Düsterhus