Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:102324
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.215.48 as permitted sender)
MIME-Version: 1.0
References: <75db877c-ef0b-7d3b-48a8-9879d90352b0@web.de> <76e4744f-6722-ee49-0325-e4433236f1b1@web.de>
 <73ac8914-8c9f-e74b-a4f5-f6e39cd96f8f@gmx.de> <3242366.BL9MUqXe46@vulcan>
 <CAFMT4Nr6B-+XwzoepUfDHuJVB9xfuJ+f-WBys_FhaERGK8gEQQ@mail.gmail.com>
 <154ba124-2915-ca36-fa39-5df6726d3b5a@web.de> <CAFMT4NrESgpg4EWoEJx=SUdBHwy0gd5jdF=ceUWneWtVfpNxsg@mail.gmail.com>
 <CALKiJKrXXktTXT05knMud3wBYoMQcMBSKrRy7ZhRT7_s8iEGUg@mail.gmail.com>
In-Reply-To: <CALKiJKrXXktTXT05knMud3wBYoMQcMBSKrRy7ZhRT7_s8iEGUg@mail.gmail.com>
Date: Wed, 20 Jun 2018 08:10:44 -0600
Message-ID: <CAFMT4Np+8WNRvB7VwDULVQ4Xzs6FHxb0ExGHunn5yqDNns8zgA@mail.gmail.com>
To: Rowan Collins <rowan.collins@gmail.com>
Cc: enno.woortmann@web.de, internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] [RFC][Under Discussion] Add functions
 array_key_first()and array_key_last()
From: levim@php.net (Levi Morrison)

On Wed, Jun 20, 2018 at 8:09 AM Rowan Collins <rowan.collins@gmail.com> wrote:
>
> On 20 June 2018 at 14:55, Levi Morrison <levim@php.net> wrote:
>>
>>
>>     if ([$key, $value] = array_last($input) {
>>         // do something
>>     }
>>
>
>
> Unfortunately, this won't work. I didn't know list() could even be used as an expression, but apparently if it is, it evaluates to the whole array on its right-hand side, which makes sense.
>
> So, if array_last([]) returns [null, null], then [$key, $value]=array_last([]) will also evaluate to [null, null]. Since that's not an empty array (it has two elements in it), it will evaluate to true. https://3v4l.org/lIEa1
>
> If, on the other hand, array_last([]) returned something empty, like [], the list() assignment would throw Notices for the implicit access to elements [0] and [1] of the empty array. https://3v4l.org/qhq5R

It returns `?array`. So either `null` or `[$key, $value]`. There are
no notices; sorry for the lack of detail.