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To: Nikita Popov <nikita.ppv@gmail.com>
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Date: Thu, 23 May 2019 21:02:26 +0200
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Subject: Re: [PHP-DEV] Calling array_merge / array_merge_recursive without
 arguments
From: d.takken@xs4all.nl (Dik Takken)

On 21-05-19 10:29, Nikita Popov wrote:
> This one makes sense in theory, because array_map(null, ...$arrays) is a
> way to perform a zip operation in PHP. Unfortunately there is an ugly
> special case if there is only a single array, which makes this not actually
> usable in practice, unless you know that there are at least two arrays. As
> such, accepting zero arrays wouldn't be very useful unless we also want to
> fix that issue (PHP 8 maybe?)

Ah, I overlooked that edge case. Indeed, array_map() would require more
fixing than I anticipated. I guess it is out of scope for the type of
fix we are discussing.

>> array_diff() & friends
> 
> array_intersect() & friends
> 
> 
> These look like good candidates for allowing a single arg.

For array_intersect(), I was actually considering to allow zero
arguments. The use case I have in mind is to determine the common
elements in a set of zero or more arrays, like this:

    array_intersect(...$arrays)

If that would just return an empty array when $arrays is empty, no
additional empty check is needed and the above would do what I
intuitively expect it to do.