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Date: Sun, 15 Aug 2021 04:24:53 -0400
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To: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Never For Argument Types
From: ondrej@mirtes.cz (=?UTF-8?Q?Ond=C5=99ej_Mirtes?=)

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It=E2=80=99s true that having =E2=80=9Cnever=E2=80=9D in a parameter type (=
please use =E2=80=9Cparameter=E2=80=9D
name for the method declaration, =E2=80=9Cargument=E2=80=9D is what you pas=
s to a parameter
when you call the method) would allow to use any type in an overriding
method from contravariance/LSP point of view. But at the same time the
interface with the =E2=80=9Cnever=E2=80=9D parameter type isn=E2=80=99t use=
ful at all, because
=E2=80=9Cnever=E2=80=9D cannot accept any type.

Same as =E2=80=9Cnever=E2=80=9D in a return type means =E2=80=9Cthis functi=
on never returns=E2=80=9D,
=E2=80=9Cnever=E2=80=9D in a parameter type means =E2=80=9Cyou can never ca=
ll this=E2=80=9D.

That=E2=80=99s because if you have interface =E2=80=9CFoo" with method "doF=
oo(never $a):
void=E2=80=9D, you might be able to override it with =E2=80=9Cclass Bar imp=
lements Foo=E2=80=9D and
method =E2=80=9CdoFoo(A $a)=E2=80=9D, but at the same time it only allows y=
ou to call
=E2=80=9CBar::doFoo(new A())=E2=80=9D, it doesn=E2=80=99t allow you to call=
 =E2=80=9CFoo::doFoo(new A())=E2=80=9D.
Which is probably not what people expect from a polymorphic method. So
having the method on the interface =E2=80=9CFoo=E2=80=9D is completely usel=
ess.

Ond=C5=99ej Mirtes

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