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Date: Mon, 22 Jan 2024 18:33:31 +0000
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Subject: Re: [PHP-DEV] [RFC] Deprecate implicitly nullable parameter type
From: rowan.collins@gmail.com (Rowan Tommins)

On 22 January 2024 10:21:12 GMT, tag Knife <fenniclog@gmail=2Ecom> wrote:
>As you are mistaking `iint $var =3D null` params as "nullable"=2E Which t=
hey
>are not, they are "optional default" parameters=2E

The feature which is being discussed is that, for the specific case of "=
=3D null", the parameter is made both optional *and* nullable=2E

To make it clearer, the following all declare default values within the al=
lowed type:

int $foo =3D 1
int|string $foo =3D 'hello'
?int $foo =3D 1
?int $foo =3D null

The following all lead to a type error, because the default value isn't al=
lowed for the declared type:

int $foo =3D 'hello'
int|string $foo =3D new DateTime;
?int $foo =3D 'hello'

However, there is a special case: for purely historical reasons, a default=
 of null is allowed *even when it doesn't match the declared type*:

int $foo =3D null
int|string $foo =3D null

These are processed as though they were declared as nullable types; and th=
e fix for the proposed deprecation would be to do so:

?int $foo =3D null
int|string|null $foo =3D null

The fact that the feature is tricky to explain is a good reason to depreca=
te it, and I think I support the proposal unless I see a good argument agai=
nst=2E

Regards,

--=20
Rowan Tommins
[IMSoP]