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Date: Wed, 20 Mar 2024 13:51:15 +0100
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Subject: Re: [PHP-DEV] Proposal: AS assertions
To: "Rowan Tommins [IMSoP]" <imsop.php@rwec.co.uk>
Cc: internals@lists.php.net
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From: landers.robert@gmail.com (Robert Landers)

On Wed, Mar 20, 2024 at 1:47=E2=80=AFPM Robert Landers <landers.robert@gmai=
l.com> wrote:
>
> On Tue, Mar 19, 2024 at 10:06=E2=80=AFPM Rowan Tommins [IMSoP]
> <imsop.php@rwec.co.uk> wrote:
> >
> > On 19/03/2024 16:24, Robert Landers wrote:
> >
> > $x =3D $attributeReflection->newInstance() as ?MyAttribute;
> > if ($x =3D=3D=3D null) // do something since the attribute isn't MyAttr=
ibute
> >
> >
> > I think reusing nullability for this would be a mistake - ideally, the =
right-hand side should allow any type, so "$foo as ?Foo" should mean the sa=
me as "$foo as Foo|null".
> >
> >
> > A better alternative might be to specify a default when the type didn't=
 match:
> >
> > $x =3D $attributeReflection->newInstance() as ?MyAttribute else null;
> > if ($x =3D=3D=3D null) // do something since the attribute isn't MyAttr=
ibute
>
> At that point, you are just reinventing already existing things. If
> you wanted to do something like that with my proposal:
>
> $x =3D $attributeReflection->newInstance() as ?MyAttribute ??
> MyAttribute::createDefault();
>
> Robert Landers
> Software Engineer
> Utrecht NL

Oh and there isn't any difference between:

$x as ?Type

or

$x as Type|null

The codebase I work with prefers ? over |null, but they are the same.