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Date: Mon, 20 Sep 2021 13:02:12 +0300
Message-ID: <CAM0Ccxjon3Zoa1h39w-bV8h+vHO2JSGu6xkv6+errwFhnQXOfA@mail.gmail.com>
To: tyson andre <tysonandre775@hotmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Proposal: Adding an ARRAY_FILTER_REINDEX flag to array_values
From: zsidelnik@gmail.com (Eugene Sidelnyk)

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Hi, I myself faced such bugs because filter function preserves keys. From
my experience it is not that easy to locate bug like this. In my case I
rewrote solution in other way than it was originally written. Only later I
realized that root cause was array_filter

On Sun, Sep 19, 2021, 4:11 PM tyson andre <tysonandre775@hotmail.com> wrote:

> Hi internals,
>
> Currently, array_filter will always return the original keys.
> This often requires an additional wrapping call of
> array_values(array_filter(...)) to reindex the keys and return a list.
> (or applications may not realize there will be gaps in the keys until it
> causes a bug or unexpected JSON encoding, etc.)
>
> PHP is also more memory/time efficient at creating packed arrays than it
> is at creating associative arrays.
>
> What are your thoughts on adding `ARRAY_FILTER_REINDEX`, to ignore the
> original int/string keys and replace them with `0, 1, 2, ...`
>
> ```
> php > echo json_encode(array_filter([5,6,7,8], fn($value) => $value % 2 >
> 0));
> {"0":5,"2":7}
> // proposed flag
> php > echo json_encode(array_filter([5,6,7,8], fn($value) => $value % 2 >
> 0, ARRAY_FILTER_REINDEX));
> [5,7]
> ```
>
> https://www.php.net/array_filter already has the `int $mode = 0` which
> accepts the bit flags `ARRAY_FILTER_USE_KEY` and `ARRAY_FILTER_USE_BOTH`
> These could be then be combined with the proposed bit flag
> `ARRAY_FILTER_REINDEX`, e.g. to filter an array based on both the array
> keys and values, and return a list without gaps.
> (and if $callback is null, this would return a list containing only the
> truthy values)
>
> Thoughts?
>
> Thanks,
> Tyson
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