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Message-ID: <94748D59-630B-4EE2-8106-B68AA4E449D2@benramsey.com>
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Date: Sun, 20 Dec 2020 20:09:46 -0600
In-Reply-To: <DM6PR07MB6618468A8C4A49818C4E2EB0F9C10@DM6PR07MB6618.namprd07.prod.outlook.com>
Cc: "internals@lists.php.net" <internals@lists.php.net>
To: tyson andre <tysonandre775@hotmail.com>
References: <DM6PR07MB6618468A8C4A49818C4E2EB0F9C10@DM6PR07MB6618.namprd07.prod.outlook.com>
Subject: Re: [PHP-DEV] [RFC] Add is_list(mixed $value): bool to check for
 list-like arrays
From: ben@benramsey.com (Ben Ramsey)

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> On Dec 19, 2020, at 19:43, tyson andre <tysonandre775@hotmail.com>
> wrote:
>=20
> It can be useful to verify that the assumption that array keys are
> consecutive integers is correct, both for data that is being passed
> into a module or for validating data before returning it from a
> module. However, because it's currently inconvenient to do that, this
> has rarely been done in my experience.

I think there are some places where `is_list()` could be unintuitive to
those who don=E2=80=99t understand some of the idiosyncrasies of PHP.

For example, with

    $a =3D ['foo', 'bar', 'baz=E2=80=99];

`is_list()` will return `true`, but if you run `$a` through `asort()`,
`is_list()` will return `false` because the keys are no longer
consecutive integers, but is there any doubt this is still a list?
Maybe in a pure sense, it=E2=80=99s not, but I think this could be =
confusing.

But now, if we do

    $b =3D array_merge($a, ['qux', 'quux']);

`$b` is now back to being a list, so `is_list($b)` returns `true`.

While I understand the convenience `is_list()` provides--I myself have
implemented the opposite of this numerous times (e.g.,
`is_dict()`)--it comes close to implying a data type that PHP doesn=E2=80=99=
t
have, and I think this could give a false sense of type-safety-ness
when using this function to check whether something is a 0-indexed
array.

Cheers,
Ben


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