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To: Kamil Tekiela <tekiela246@gmail.com>
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Subject: Re: [PHP-DEV] Disable autovivification on false
From: dusk@woofle.net (Dusk)

On May 25, 2021, at 09:23, Kamil Tekiela <tekiela246@gmail.com> wrote:
> I'd like to start a discussion on the following RFC
> https://wiki.php.net/rfc/autovivification_false
> Particularly, I am looking for opinions on whether this behaviour =
should be
> left alone, should be disabled on false, or should be disabled on null =
and
> false, and left only for undefined variables.

It seems to me there are two different sorts of autovivification which =
can happen. (They may actually be the same thing under the hood, but =
they feel different to me.)

One is autovivification within an array, e.g.

    $x =3D ["b" =3D> null, "c" =3D> false];
    $x["a"][] =3D 1; // from unset
    $x["b"][] =3D 2; // from null
    $x["c"][] =3D 3; // from false

The other is autovivification on values outside arrays, e.g.

    $b =3D null; $c =3D false; $d =3D new stdClass();
    $a[] =3D 1; // from unset
    $b[] =3D 2; // from null
    $c[] =3D 3; // from false
    $obj->a[] =3D 4; // from unset on an object property, same idea

(The same behavior occurs in each case if an explicit key is used =
instead of [].)

=46rom my perspective, the latter is much more concerning than the =
former. Adding dimensions to an existing array feels like less of a =
type-correctness violation than calling an entire array into existence =
where a non-array value (or no value at all) existed before.=