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Date: Sat, 9 Dec 2017 11:21:49 +0100
Message-ID: <CADyq6sKeqMU3tEOpj7auRta8socNm3AwtJ3ZvWtdnmQd-T28Uw@mail.gmail.com>
To: Andreas Hennings <andreas@dqxtech.net>
Cc: Kalle Sommer Nielsen <kalle@php.net>, PHP Internals List <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="001a114cc6c46e1616055fe5ab8a"
Subject: Re: [PHP-DEV] instanceof survives non-object variables, but crashes
 on non-object constants.
From: ocramius@gmail.com (Marco Pivetta)

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The typical usage of `instanceof` is checking a `null|object` API that
built an object of a (presumably known) type. Adding a crash there seems
silly and overcomplicated.

On 9 Dec 2017 07:57, "Andreas Hennings" <andreas@dqxtech.net> wrote:

> 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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