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Date: Thu, 16 Mar 2017 00:33:10 +0100
Message-ID: <CADyq6sKEex_d9m3Coat6aRMz+Ao9f9nHvOVKmoJCZC2=wZGrpw@mail.gmail.com>
To: Ryan Pallas <derokorian@gmail.com>
Cc: =?UTF-8?Q?Beno=C3=AEt_Burnichon?= <bburnichon@gmail.com>, 
	Kalle Sommer Nielsen <kalle@php.net>, internals@lists.php.net
Content-Type: multipart/alternative; boundary=001a114961cc1e99f2054acd5eab
Subject: Re: [PHP-DEV] Add __toArray() method to objects that would be called
 on cast to array
From: ocramius@gmail.com (Marco Pivetta)

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Content-Type: text/plain; charset=UTF-8

Correct: passing an object that implements `__toArray()` to an API that
uses an `(array)` cast internally will break or misbehave, if this feature
is added to the language.

On 16 Mar 2017 12:27 a.m., "Ryan Pallas" <derokorian@gmail.com> wrote:

>
>
> On Mar 15, 2017 5:03 PM, "Marco Pivetta" <ocramius@gmail.com> wrote:
>
> Hi Ryan,
>
> I'm top-posting because I'm writing from a phone. I always do and I also
> stopped caring for top-posters myself because it's fairly normal, plus
> modern email clients deal with it. If I can write a damn mail from a phone
> keyboard because I don't have any better right now, then you can probably
> use the scroll wheel once on your pc too.
>
> I'll just say this: I'm also on a mobile device. Don't make assumptions.
>
>
> The BC break applies to API that accepts `object` (any object). Such API
> is common in library code in frameworks, data-mappers, etc.
>
> Such code would not work anymore for cases where the magic method is
> implemented, adding either exceptions (forcing a library-level BC break) or
> simply by causing the existing stable versions of these libs to be
> incompatible with newer php versions.
>
>
> I must misunderstand what constitutes an BC break. I thought a BC break
> was when identical code produced different results. But you're saying its a
> break because someone could change their code to use a new feature and
> break their use of your library?
>
>
>
>
> On 15 Mar 2017 11:57 p.m., "Ryan Pallas" <derokorian@gmail.com> wrote:
>
>
>
> On Mar 15, 2017 16:40, "Marco Pivetta" <ocramius@gmail.com> wrote:
>
> Which is precisely the BC break: such a library would now throw an
> exception "unsupported class X" when `__toString` is implemented. Also,
> such a library would break silently when this feature is implemented.
>
> Much like the already very broken `__debugInfo()`, this automatic
> type-cast is a giga-Joule footgun.
>
>
> First please stop top posting.
>
> Second bc means that if no code changes no functionality is changed.
> That's exactly what we're talking about. If the class doesn't change
> neither does the functionality. So unless classes already have __toArray
> they will not change in behaviour.
>
> As pointed out in answer to my question earlier a class with no code
> change would see no change in casting behaviour. Only if new method is
> implemented will behaviour change. How does that not maintain bc?
>
>
> On 15 Mar 2017 11:36 p.m., "Ryan Pallas" <derokorian@gmail.com> wrote:
>
>>
>>
>> On Wed, Mar 15, 2017 at 4:33 PM, Marco Pivetta <ocramius@gmail.com>
>> wrote:
>>
>>> It's the only way to distinguish between set and unset properties. Also
>>> the
>>> only way to get all properties from an instance of an inheritance tree.
>>
>> Also, it's covered by tests that were explicitly added to prevent
>>> regressions on this.
>>>
>>> Same as all similar discussions before this one: need an alternative way
>>> to
>>> do things before proposing a BC break.
>>>
>>>
>> As mentioned in previous mails - the intent isn't to change existing
>> behaviour, but to provide a way for a class to override the default
>> behaviour. As long as those classes you are casting to array don't
>> implement __toArray they will behave exactly as they always have. The only
>> concern then, is that you might be relying on a library to not implement
>> that function on a class you are casting.
>>
>>
>>> On 15 Mar 2017 11:27 p.m., "Kalle Sommer Nielsen" <kalle@php.net> wrote:
>>>
>>> > Hi
>>> >
>>> > 2017-03-15 21:41 GMT+01:00 Marco Pivetta <ocramius@gmail.com>:
>>> > > This is a BC break due to the fact that the `(array)` cast is used to
>>> > > extract property information from private properties in library code.
>>>
>> >
>>> > Yep, but then again that is more of an
>>> > undocumented-not-really-supported case afair, if anything then
>>> > Reflection should have the APIs to officially allow that, although I
>>> > am still skeptic of this.
>>>
>> Does it not through get properties?
>
> >
>>> >
>>> > --
>>> > regards,
>>> >
>>> > Kalle Sommer Nielsen
>>> > kalle@php.net
>>> >
>>>
>>
>>
>
>
>

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