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To: Nikita Popov <nikita.ppv@gmail.com>
CC: PHP internals <internals@lists.php.net>
Thread-Topic: [PHP-DEV] Warn when declaring required parameter after optional
 one
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Date: Thu, 9 Jan 2020 13:41:34 +0000
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Subject: Re: [PHP-DEV] Warn when declaring required parameter after optional
 one
From: bobwei9@hotmail.com (Bob Weinand)

Hey,

While I generally agree that it likely is a bug in new code, I would rather=
 deprecate it than warn or even error: the change would make it impossible =
to retain a type without warning while preserving compatibility with an old=
 PHP version and making incremental migrations harder (would then not be po=
ssible to write warning-free code running on 7.0 and 8.0 at the same time w=
hile retaining type information).

I would like to see it deprecated and then removed in 4+ years.

Bob

> Am 09.01.2020 um 13:27 schrieb Nikita Popov <nikita.ppv@gmail.com>:
>=20
> Hi internals,
>=20
> I've created https://github.com/php/php-src/pull/5067 to make code like
>=20
>    function test($foo =3D null, $bar) {}
>=20
> throw a warning:
>=20
>    Warning: Required parameter $bar follows optional parameter
>=20
> Historically, having an "optional" parameter before a required one was
> useful for poor man's nullable types. That is, one could write
>=20
>    function test(FooBar $param =3D null, $param2)
>=20
> to get an effective
>=20
>    function test(?FooBar $param, $param2)
>=20
> signature on old PHP versions that did not have native support for nullab=
le
> types.
>=20
> Since nullable types have been available since PHP 7.1, having a required
> parameter after an optional one is increasingly likely a bug rather than =
an
> intentional workaround, so I think it would be good to throw a warning fo=
r
> this case.
>=20
> What do you think?
>=20
> Nikita