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Date: Tue, 17 Oct 2023 12:34:38 -0400
To: "Saki Takamachi" <saki@sakiot.com>
Cc: "Levi Morrison" <levi.morrison@datadoghq.com>,
 "David Grudl" <david@grudl.com>,
 "Levi Morrison via internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Two new functions array_first() and array_last()
From: php@mjec.net ("Michael Cordover")

On Tue, Oct 17, 2023, at 12:19, Saki Takamachi wrote:
>> What about a signature like:
>>=20
>> ```php
>> array_first(array $array, mixed $value_if_missing =3D null);
>> ```
>>=20
>> That would let you specify your own sentinel (or default) where appro=
priate, without losing the convenience of this function.
>
> This is a problem that should be addressed in your application.
>
> ```
> array_first($arr) ?? $initial
> ```
>
> I personally think we should make the effort to write it this way and=20
> not have to support initial values =E2=80=8B=E2=80=8Bat the language l=
evel.

The problem Levi mentioned is that there's ambiguity in this constructio=
n: if the valid data domain for elements of `$arr` includes `null`, then=
 you can't tell whether the null comes from the array being empty, or fr=
om its first value being null. In other words, there exists application =
code where using `??` in this way is unsuitable.

I can think of three approaches for dealing with this, resulting in appl=
ication code like:

```
$value =3D array_first($arr, $default);

$value =3D count($arr) > 0 ? array_first($arr) : $default;

try {
  $value =3D array_first($arr);
} catch (OutOfBoundsException $e) {
  $value =3D $default;
}
```

I think the first of those - what I initially suggested - is the cleanes=
t.

mjec