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Date: Thu, 16 Mar 2017 11:34:25 -0300
Message-ID: <CAOsHV+vqp3pwMi91mXLa5nEou0mRrhQKc7NPBAp-na1qFfVqzA@mail.gmail.com>
To: Marco Pivetta <ocramius@gmail.com>
Cc: Andrey Andreev <narf@devilix.net>, Ryan Pallas <derokorian@gmail.com>, 
	PHP Internals List <internals@lists.php.net>, =?UTF-8?Q?Beno=C3=AEt_Burnichon?= <bburnichon@gmail.com>, 
	Kalle Sommer Nielsen <kalle@php.net>
Content-Type: multipart/alternative; boundary=94eb2c07b87462eb81054ad9f6b8
Subject: Re: [PHP-DEV] Add __toArray() method to objects that would be called
 on cast to array
From: marcio.web2@gmail.com (Marcio Almada)

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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

2017-03-16 11:01 GMT-03:00 Marco Pivetta <ocramius@gmail.com>:

> Since some folks keep banging on "it's not a BC break", I propose a
> challenge in fixing this particular BC break example (reads: find a
> different way to make it work, and no warnings/notices allowed):
>
> I made a very simplistic example of where `__toArray` will break existing
> API that currently literally accepts any kind of object:
> https://3v4l.org/Tj0GH
>
> For reference, here's the code copy:
>
> <?php
>
> class Foo
> {
>     public $bar;
>     public $baz;
>     public $taz;
> }
>
> // please note that this API has a signature of `object $object` - any
> object allowed.
> function unsetProperties($object) {
>     // we ignore inheritance and private properties for simplicity
>     return array_diff(
>         array_map(
>             function (\ReflectionProperty $p) : string {
>                 return $p->getName();
>             },
>             (new ReflectionClass($object))->getProperties()
>         ),
>         array_keys((array) $object)
>     );
> }
>
> var_dump(unsetProperties(new Foo));
>
> $foo =3D new Foo;
>
> unset($foo->baz);
>
> var_dump(unsetProperties($foo));
>
> There are dozens of simpler examples that break (typically, data-mapper
> layers): I picked this particular one because there is no other way to
> detect unset properties without causing side-effects.
>
> If `__toArray` is implemented on an object, the API defined above will
> either report all properties to be unset, or in general produce unreliabl=
e
> results.
>
> The current API specification of the `(array)` operator is as following:
>
>  * for every SET property produce an array value, with the key being:
>     * "\0" . $className . "\0" . $propertyName for private properties
>     * "\0*\0" . $propertyName for protected properties
>     * $propertyName for public properties
>     * $propertyName for dynamically defined properties
>
> This is a **VERY SPECIFIC** behavior that the operator currently
> guarantees. Break that, and you can go on github hunting for `(array)` ca=
st
> usages.
>
> The behavior was frozen in the current suite in
> https://github.com/php/php-
> src/blob/8015daeddb7bb4951c808fa253b97753787fb0ea/tests/classes/
> <https://github.com/php/php-%0Asrc/blob/8015daeddb7bb4951c808fa253b977537=
87fb0ea/tests/classes/>
> array_conversion_keys.phpt (although, now that I notice, doesn't cover
> dynamically defined properties - should add that).
>
> Marco Pivetta
>
> http://twitter.com/Ocramius
>
> http://ocramius.github.com/
>

I kinda agree that (array) being aware of toArray() is not a very good idea
at this point, but...

It's still not a BC break. In order for the output of "(array) $obj" to
change, one would need to change the implementation of the subject $obj
class. Lawyering this as a BC break will just hurt any possibility of
advancing the conversation in any direction.

IMMO, if anyone would like to proceed with this toArray() proposal, a
better object reflection/destructuring API could be provided first.

Thanks,
M=C3=A1rcio.

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