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Date: Sat, 14 Oct 2023 22:29:28 +0200
To: "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: nikita.ppv@gmail.com ("Nikita Popov")

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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

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