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Thread-Topic: [PHP-DEV] Array spread append
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Date: Thu, 6 Apr 2023 11:52:49 +0000
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Subject: Re: [PHP-DEV] Array spread append
From: vorismi3@fjfi.cvut.cz ("Vorisek, Michael")

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Hi Ilija,

* Are integer keys preserved? I'm assuming no, as otherwise it would
be the same as `$a + $b`.

$arr[...] =3D $arr;
should be the same as
foreach ($arr as $v) { $arr[] =3D $v; }

all other answers should be answered from this and consistency

* What is the return value of the expression `$a[...] =3D $b`? I'm
assuming $a after the additions of $b?

https://3v4l.org/63IEU - the right side expr to be consistent with regular =
$arr[] =3D expr

* How does it behave in combination with `ArrayAccess`? Throw? Call
`offsetSet` for each element?

https://3v4l.org/v26Bh - call `offsetSet` for each element

* How does it interact with references? E.g. This is valid PHP code:
`assign_by_ref($a[])` (https://3v4l.org/qoJYn)

`assign_by_ref($a[...])` would be about the same as `assign_by_ref($a)`, so=
 compile error

* How does it interact with undefined/null values? E.g. `$a[] =3D 42;`
works without declaring $a first.

https://3v4l.org/JtO7g - same behaviour, based on the foreach definition

* Is there a need for this? Given that `+` doesn't work with
sequential lists and `array_push($a, ...$b)` doesn't work with strings
I'd say possibly. `[...$a, ...$b]` works but requires duplication of
the array which in loops can be detrimental to performance.

Yes, `+` and/or `array_push($a, ...$b)` are not equivalents, and all other =
syntaxes like
`[...$a, ...$b]` or `array_merge($a, $b)` are longer to write and slower

* One extra QA about references:

https://3v4l.org/U02Cq - `$arr[...] =3D &$arr` should be compile error

Michael
________________________________
From: Ilija Tovilo <tovilo.ilija@gmail.com>
Sent: Thursday, April 6, 2023 12:18 PM
To: internals@lists.php.net <internals@lists.php.net>
Subject: Re: [PHP-DEV] Array spread append

Hi Michael

> I would like to open a discussion for https://github.com/php/php-src/issu=
es/10791 .
> [https://opengraph.githubassets.com/a23cb565cc8acac6a33ecab5d9ee68a46f046=
a1ffe215501673156e506695430/php/php-src/issues/10791]<https://github.com/ph=
p/php-src/issues/10791>
> Array spread append =B7 Issue #10791 =B7 php/php-src<https://github.com/p=
hp/php-src/issues/10791>
> Description Currently spread operator can be used for almost anything. Bu=
t not for array append. I propose the following to be supported: <?php $arr=
 =3D [1, 2]; $arr2 =3D [3, 4]; $arr[...] =3D $arr2; // ...
> github.com
> Appending N elements to an array is quite common language usage pattern a=
nd I belive it should be supported natively for shorter syntax, language co=
nsistency and performance.Hi Michael

There are a few questions that come to mind (there may be more).

* Are integer keys preserved? I'm assuming no, as otherwise it would
be the same as `$a + $b`.
* What is the return value of the expression `$a[...] =3D $b`? I'm
assuming $a after the additions of $b?
* How does it behave in combination with `ArrayAccess`? Throw? Call
`offsetSet` for each element?
* How does it interact with references? E.g. This is valid PHP code:
`assign_by_ref($a[])` (https://3v4l.org/qoJYn)
* How does it interact with undefined/null values? E.g. `$a[] =3D 42;`
works without declaring $a first.
* Is there a need for this? Given that `+` doesn't work with
sequential lists and `array_push($a, ...$b)` doesn't work with strings
I'd say possibly. `[...$a, ...$b]` works but requires duplication of
the array which in loops can be detrimental to performance.

Ilija

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