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Date: Sun, 15 Oct 2023 14:40:11 +0200
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To: Ben Ramsey <ben@benramsey.com>, Nikita Popov <nikita.ppv@gmail.com>
Cc: David Grudl <david@grudl.com>, Levi Morrison <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Two new functions array_first() and array_last()
From: pierre-php@processus.org (Pierre)

Le 15/10/2023 à 01:11, Ben Ramsey a écrit :
>> On Oct 14, 2023, at 16:30, Nikita Popov <nikita.ppv@gmail.com> wrote:
>>
>> ﻿On Sat, Oct 14, 2023, at 20:00, David Grudl wrote:
>>> PHP lacks two very basic functions for working with arrays:
>>>
>>> - array_first() returning the first element of an array (or null)
>>> - array_last() returning the last element of the array (or null)
>>>
>>> While PHP has functions that return the first and last keys,
>>> array_key_first() and array_key_last(), it does not have more useful
>>> functions for values.
>>>
>>> a) What about reset() and end()?
>>> Programmers "abuse" the reset() and end() functions for this purpose.
>>> The problem is that these functions are used to move the internal
>>> pointer in the array. Which is why they have a name that is
>>> inappropriate when used in the sense of "return me the first element".
>>>
>>> Much worse, they shouldn't to be used to get first/last value, because
>>> they have a side effect (i.e. moving the pointer).
>>>
>>> Further, in the absence of an element, they return the obsolete false
>>> and not the currently expected null, which can be combined with the ??
>>> operator. In this they differ from the similar functions
>>> array_key_first() and array_key_last().
>>>
>>> b) What about $array[array_key_first($array)]?
>>>
>>> For such basic functions as returning the first and last item in an
>>> array, there should be a function in the basic package, not a
>>> workaround. Moreover, this requires having the array in a local
>>> variable, since $this->getFoo()[array_key_first($this->getFoo())]
>>> would be very inefficient and possibly incorrect.
>>>
>>> c) Two such functions were proposed and rejected during the
>>> array_key_first/last RFC
>>> (https://wiki.php.net/rfc/array_key_first_last)
>>>
>>> Yes, that was in 2018. At that time, functions like str_contains() or
>>> str_starts_with() wouldn't have even come into existence, just because
>>> there was an obscure way to do it without them. I believe we've moved
>>> on since then. Today we know how useful it is to use simple,
>>> easy-to-understand methods, both for programmers who write and read
>>> the code.
>>>
>>> DG
>> I'm in favor of adding these.
>>
>> To add to what you already said, because reset/end modify the array, there's a good chance that calling these functions will copy the whole array due to a modification you are not actually interested in.
>>
>> So basically you have the choice between calling end(), which is the wrong thing to do semantically and may be slow, or using $array[array_key_last($array)], which is rather convoluted, and incorrect if the array is potentially empty.
>>
>> Regards,
>> Nikita
> I’m in favor of these functions, for all the same aforementioned reasons.

Yes please !

array_first() and array_last() are definitely needed. I wrote `foreach 
($foo as $value) break;` too many times in my life. array_key_first() 
and array_key_last() I wouldn't use it much, but they'd probably  find 
their use cases as well.

The first two probably only make sense for a numerically indexed array, 
so I guess that array_is_list() (whatever the name is, I don't want to 
bikeshed about naming) would be a good addition as well, that, in my 
opinion, would be pertinent to add at the same time.

Regards,

Pierre