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In-Reply-To: <154ba124-2915-ca36-fa39-5df6726d3b5a@web.de>
Date: Wed, 20 Jun 2018 07:55:00 -0600
Message-ID: <CAFMT4NrESgpg4EWoEJx=SUdBHwy0gd5jdF=ceUWneWtVfpNxsg@mail.gmail.com>
To: enno.woortmann@web.de
Cc: 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 3:17 AM Woortmann, Enno <enno.woortmann@web.de> wrote:
>
> Hi Levi,
>
>
> Am 20.06.2018 um 04:47 schrieb Levi Morrison:
> >      list($key, $value) = array_first($input);
> >      // $key will be null if the call failed
> >
> >      list($key, $value) = array_last($input);
> >      // $key will be null if the call failed
>
> Your proposed functions would be implementable with the internal
> functions but I think this approach doesn't provide a clean function
> interface as it forces the user to evaluate the wanted value from the
> returned array structure by using either the list() construct or
> something like $key = array_first($input)[0];
>
> I believe two functions with this interface will be confusing and less
> intuitive for the developer.
> If I use a function I expect it to give me a return value which I can
> use without any further post processing $wantedValue =
> fancyFunction($someInput);

Your wish cannot be granted for `array_value_last` and
`array_value_first`; you cannot know by itself if there is a failure
condition. As proposed you have to write:

    if (!empty($input)) {
        $value = array_value_last($input)
        // do something
    }

This is not "clean". In contrast here is with my proposal:

    if ([$key, $value] = array_last($input) {
        // do something
    }

If I need the last/first key and value (which is a real use-case and
why I thought of this in the first place) then in your proposal I have
to do:

    if (!empty($input)) {
        $key = array_key_last($input);
        $value = array_value_last($input);
   }

Or use the key to get the value; roughly the same amount of code.
Either way is not as clean as:

    if ([$key, $value] = array_last($input) {
        // do something
    }

Hopefully I have shown that for various use-cases the proposed
interface is cleaner and that you cannot argue against it on those
grounds.

Adding 4 functions which cover 4 use-cases, with ugly names, and 2 of
them having poor failure semantics is not a good direction. Adding
only 2 functions which cover 6 use-cases, with nice names, and good
failure conditions is better. Please reconsider.