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Array map with reset function

php.internals

Michael Voříšek - ČVUT FEL

6 years ago

The following code stopped working in PHP 8:

https://3v4l.org/UlIE3

is it a bug or a feature?

is posting issues like this to internals@lists.php.net email prefered
over opening bug directly? or is there any special email for it?

With kind regards / Mit freundlichen Grüßen / S přátelským pozdravem,

Michael Voříšek

Unnamed Person

6 years ago

On Tue, Aug 25, 2020 at 11:47 AM Michael Voříšek - ČVUT FEL
<vorismi3@fel.cvut.cz> wrote:

>
> The following code stopped working in PHP 8:
>
> https://3v4l.org/UlIE3
>
> is it a bug or a feature?
>
> is posting issues like this to internals@lists.php.net email prefered
> over opening bug directly? or is there any special email for it?
>
> With kind regards / Mit freundlichen Grüßen / S přátelským pozdravem,
>
> Michael Voříšek

The documentation for array_map doesn't mention references at all. I'm
inclined to believe it to be an intentional warning, but it may be a
regression.

I recommend using array_walk, as it _does_ mention reference support.

Nikita Popov

6 years ago

On Tue, Aug 25, 2020 at 7:47 PM Michael Voříšek - ČVUT FEL <
vorismi3@fel.cvut.cz> wrote:

> The following code stopped working in PHP 8:
>
> https://3v4l.org/UlIE3
>
> is it a bug or a feature?
>

This is an intentional change, if that's what you're asking. array_map() is
not spec'd to pass by reference, so it doesn't.

is posting issues like this to internals@lists.php.net email prefered

> over opening bug directly? or is there any special email for it?
>

Please prefer reporting issues at bugs.php.net over this mailing list. (At
least for bugs -- for non-trivial feature requests, the mailing list may be
better.)

Regards,
Nikita

Rowan Collins

6 years ago

On Tue, 25 Aug 2020 at 20:08, Nikita Popov <nikita.ppv@gmail.com> wrote:

> On Tue, Aug 25, 2020 at 7:47 PM Michael Voříšek - ČVUT FEL <
> vorismi3@fel.cvut.cz> wrote:
>
> > The following code stopped working in PHP 8:
> >
> > https://3v4l.org/UlIE3

To be pedantic: it didn't stop working, it just started raising Warnings.
The return value of array_map remains the same.

>
> >
> > is it a bug or a feature?
> >
>
> This is an intentional change, if that's what you're asking. array_map() is
> not spec'd to pass by reference, so it doesn't.
>

As with many uses of reset(), this one doesn't really need to be by
reference, it's being used for its output. Unfortunately, array_value_first
failed at RFC [https://wiki.php.net/rfc/array_key_first_last#vote], so I
presume the recommended replacement code in the general case is this:

array_map(fn($x)=>$x[array_key_first($x)], $rows)

Of course for a list-style array like the example shown, it can be a lot
simpler:

array_map(fn($x)=>$x[0], $rows)

Regards,

--
Rowan Tommins
[IMSoP]

Alexandru Pătrănescu

6 years ago

On Wed, Aug 26, 2020 at 11:16 AM Rowan Tommins <rowan.collins@gmail.com> wrote:

>
> On Tue, 25 Aug 2020 at 20:08, Nikita Popov <nikita.ppv@gmail.com> wrote:
>
> > On Tue, Aug 25, 2020 at 7:47 PM Michael Voříšek - ČVUT FEL <
> > vorismi3@fel.cvut.cz> wrote:
> >
> > > The following code stopped working in PHP 8:
> > >
> > > https://3v4l.org/UlIE3
>
>
>
> To be pedantic: it didn't stop working, it just started raising Warnings.
> The return value of array_map remains the same.
>
>
>
> >
> > >
> > > is it a bug or a feature?
> > >
> >
> > This is an intentional change, if that's what you're asking. array_map() is
> > not spec'd to pass by reference, so it doesn't.
> >
>
>
> As with many uses of reset(), this one doesn't really need to be by
> reference, it's being used for its output. Unfortunately, array_value_first
> failed at RFC [https://wiki.php.net/rfc/array_key_first_last#vote], so I
> presume the recommended replacement code in the general case is this:
>
> array_map(fn($x)=>$x[array_key_first($x)], $rows)
>
> Of course for a list-style array like the example shown, it can be a lot
> simpler:
>
> array_map(fn($x)=>$x[0], $rows)
>
> Regards,
> --
> Rowan Tommins
> [IMSoP]

array_map(fn($x)=>reset($x), $rows) would work as well

Alex