Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:102828
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.218.46 as permitted sender)
MIME-Version: 1.0
In-Reply-To: <CAFMT4NoV1VtUJToGa_gVP2=kTm08Vc-DY7c2gKFNHoBdFZMHmA@mail.gmail.com>
References: <e8fdd7ca-135a-2a7f-79cd-e45486f4ba8b@web.de> <CAFMT4Nqyc=iJHWTPtQs_Sw=PfxsAoNkXc1Q4JKcedw2sziLbJg@mail.gmail.com>
 <CAFMT4NrMKq3aWUyk_mf-nLKmo6Nqes7OSNBmwTz8Npcsg-k=-w@mail.gmail.com> <CAFMT4NoV1VtUJToGa_gVP2=kTm08Vc-DY7c2gKFNHoBdFZMHmA@mail.gmail.com>
Date: Sat, 14 Jul 2018 19:07:14 -0300
Message-ID: <CANA3Deu79PGHYAo8EKcr_RaenuSHZD_BnMBgjdyPTHpEREQW8g@mail.gmail.com>
To: Levi Morrison <levim@php.net>
Cc: enno.woortmann@web.de, internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000de64240570fcd2e4"
Subject: Re: [PHP-DEV] [VOTE] array_key_first(), array_key_last(),
 array_value_first(), array_value_last()
From: marcospassos.com@gmail.com (Marcos Passos)

--000000000000de64240570fcd2e4
Content-Type: text/plain; charset="UTF-8"

A function like array_offset would be convenient as there is no way to
access the value of an array entry by its index currently. The workaround
is using array_slice, with all the downsides already pointed out.

2018-07-13 20:04 GMT-03:00 Levi Morrison <levim@php.net>:

> On Fri, Jul 13, 2018 at 4:50 PM Levi Morrison <levim@php.net> wrote:
> >
> > On Fri, Jul 13, 2018 at 4:48 PM Levi Morrison <levim@php.net> wrote:
> > >
> > > On Mon, Jul 9, 2018 at 5:17 AM Woortmann, Enno <enno.woortmann@web.de>
> wrote:
> > > >
> > > > Hi,
> > > >
> > > > as the discussion got no new contributions I'd like to start the
> voting
> > > > for the RFC fo add new functions for the handling of outer array
> elements.
> > > >
> > > > https://wiki.php.net/rfc/array_key_first_last
> > > >
> > > > To have a better separation I split up the vote for the functions.
> The
> > > > first vote covers the functions to handle keys: array_key_first() and
> > > > array_key_last(). The second vote covers the corresponding functions
> to
> > > > handle the values: array_value_first() and array_value_last().
> > > >
> > > > As this RFC adds functions but doesn't change the language syntax a
> 50%
> > > > + 1 majority is required for both votes. The votes are open until
> > > > 2018-07-16.
> > > >
> > > > The discussion for this RFC is located at
> > > >
> > > > https://externals.io/message/102245
> > > >
> > > > Regards,
> > > >
> > > > Enno
> > > >
> > > >
> > > >
> > > >
> > > > --
> > > > PHP Internals - PHP Runtime Development Mailing List
> > > > To unsubscribe, visit: http://www.php.net/unsub.php
> > >
> > > This entire time I felt like this should be possible in pure PHP.
> > > Surely, somewhere, we have this capability already? I searched quite a
> > > few functions but didn't find anything.
> > >
> > > However, the feeling was right. Just moments ago Paul Crovella from
> > > Stack Overflow mentioned to me that `array_slice` uses the terminology
> > > `offset` to refer to the order of the entry rather than its key, so I
> > > went looking. As far as I can tell from the [array_slice
> > > implementation][1] it will not trigger copies and will be efficient if
> > > using -1 to retrieve the last index. We can provide the parameter
> > > `preserve_keys` an argument of true to get both the key and the value.
> > > These functions *are* efficiently implementable in user-land!
> > >
> > > Below is a proof-of-concept for the `array_offset` function [mentioned
> > > by Nicolas Grekas][2] (which by the way, neither the RFC author nor
> > > anyone else responded to this suggestion) that is simply a convenience
> > > wrapper over `array_slice`:
> > >
> > >     function array_offset(array $input, int $offset): ?array {
> > >         $slice = array_slice($input, $offset, 1, true);
> > >         return count($slice) ? $slice : null;
> > >     }
> > >
> > >     $assoc = ['one' => 1, 'two' => 2, 'three' => 3];
> > >     $packd = range(1, 4);
> > >
> > >     var_dump(array_offset($assoc, -1));
> > >     var_dump(array_offset($packd, -1));
> > >
> > >     var_dump(array_offset($assoc, 0));
> > >     var_dump(array_offset($packd, 0));
> > >
> > > Of course, the `array_slice` function can be used to build all of the
> > > functions described in the RFC, as well.
> > >
> > > My new opinion is that no new functions are required and that
> > > improving the `array_slice` documentation is all that is necessary. It
> > > currently does not show any examples of it working on associated
> > > arrays, which is probably why none of us (many of us experts) realized
> > > this through this discussion. This is especially true as "offset" in
> > > some other situations really means "key", as in
> > > `ArrayAccess::offsetGet`.
> > >
> > >   [1]: https://github.com/php/php-src/blob/
> b9963969fd088dca6852483fdb1c6b7e1080764d/ext/standard/array.c#L3477-L3577
> > >   [2]: https://externals.io/message/102245#102322
> >
> > Small correction: Nicolas used the name `array_index`, not
> `array_offset`.
>
> Unfortunately I was too hasty: `array_slice` will iterate over the
> entire input range:
>
>     https://github.com/php/php-src/blob/b9963969fd088dca6852483fdb1c6b
> 7e1080764d/ext/standard/array.c#L3538-L3552
>
> We could add an case for when `array_slice` uses `-1`. I wonder how
> common this already is. Does anyone have a tool that easily can search
> open source code for usages of functions? I am interested in this
> regardless of the outcome of this RFC.  The documentation for
> `array_slice` should also be updated independently of this RFC as
> well.
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>

--000000000000de64240570fcd2e4--