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Date: Sat, 9 Dec 2017 07:56:55 +0100
Message-ID: <CAH0Uv3F1ETGpKfqf58DOX02MXeF16=TGehTej3Ab0NHwrg4YJQ@mail.gmail.com>
To: Kalle Sommer Nielsen <kalle@php.net>
Cc: Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="089e08274e44b90edc055fe2cf64"
Subject: Re: [PHP-DEV] instanceof survives non-object variables, but crashes
 on non-object constants.
From: andreas@dqxtech.net (Andreas Hennings)

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Why is the usage broken? It works :)
In practice, the current version of instanceof has an is_object() built-in.
This is what people could assume from trying.

Of course I don't know how it is implemented internally. Maybe a kitten
dies every time I use instanceof on non-object variables?

If we need an additional is_object() it can make some code more expensive..




On 9 December 2017 at 07:46, Kalle Sommer Nielsen <kalle@php.net> wrote:

> Hi
>
> That is fine for code that is broken in the first place. Similarly we
> added a warning some years back about array to string conversions.
>
> If your code is like the example, it should be updated and warned about as
> you are doing something illogical by first checking the type and or value
> of the operand you are passing to instanceof after.
>
> The impact should be minimal as is, so persevering bc for broken usage is
> a poor argument imo
>
>
>
> On 9 Dec 2017 07.38, "Andreas Hennings" <andreas@dqxtech.net> wrote:
>
>> Adding a warning to something that used to be ok would break existing
>> code.
>> I remember a number of cases where I used instanceof on possibly
>> non-objects.
>>
>> if ($x instanceof C) {
>>   return $x;
>> }
>> elseif ($x === NULL) {
>>  ...
>> }
>>
>> All such code would then produce warnings.
>>
>>
>> On 9 December 2017 at 07:35, Kalle Sommer Nielsen <kalle@php.net> wrote:
>>
>>> Hi
>>>
>>> We should just add a warning to the first example, it seems like an
>>> oversight that it was left silent
>>>
>>> On 9 Dec 2017 07.29 <20%2017%2007%2029>, "Andreas Hennings" <
>>> andreas@dqxtech.net> wrote:
>>>
>>>> The following (https://3v4l.org/A2Tp6) is ok, it simply returns false:
>>>>
>>>>     $x = 1;
>>>>     $x instanceof \stdClass;
>>>>
>>>>
>>>> The following (https://3v4l.org/IdSBu) gives a fatal error:
>>>>
>>>>     1 instanceof \stdclass;
>>>>
>>>> t think this behavior is inconsistent, and we should consider changing
>>>> it.
>>>>
>>>> There are two options, but only one is BC.
>>>>
>>>> - Let 1 instanceof \stdClass return false, instead of crashing. ->
>>>> seems BC
>>>> - Let $x instanceof \stdClass crash, if $x is not an object. -> BC
>>>> break.
>>>>
>>>> So it seems the first would the option we should take.
>>>> This is also what hhvm does, according to https://3v4l.org/IdSBu.
>>>>
>>>
>>

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