Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:122929
Precedence: bulk
MIME-Version: 1.0
References: <6299b649-c19b-4172-9632-2ef0a55d256d@uzy.me>
In-Reply-To: <6299b649-c19b-4172-9632-2ef0a55d256d@uzy.me>
Date: Thu, 4 Apr 2024 06:03:17 -0700
Message-ID: <CA+pig-JBkZip5bEM0gSwcwNRO9NDKuRO2vu=iHnx2diBTv9Bng@mail.gmail.com>
Subject: Re: [PHP-DEV] RFC idea: using the void type to control maximum arity
 of user-defined functions
To: Pablo Rauzy <r@uzy.me>
Cc: internals@lists.php.net
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
From: mark@itafroma.com (Mark Trapp)

On Thu, Apr 4, 2024 at 5:43=E2=80=AFAM Pablo Rauzy <r@uzy.me> wrote:
>
> Hello all,
>
> First, I'm new here, so let me start by warmly thanking everyone
> involved in PHP development. I've started programming 22 years using it
> as my first programming language, and still enjoy using it a lot :).
>
> I've read the rfc:howto and the first step is to get feedback from this
> mailing list about the intended proposal, so here is a short description
> of what I have in mind:
>
> Currently PHP does not warn when user-defined functions are called with
> too many arguments. Changing this could break a lot of existing code,
> but it would also be a very good verification to catch potential bugs.
>
> I have an idea allowing this feature without breaking any existing code:
> using the void keyword in a function arguments list to strictly limit
> the number of arguments a user-defined function can receive, stopping it
> on the void, which could only be used once and in the last position.
>
> Currently, void is a return-only type so it isn't used in arguments list
> in existing code, so I believe the new behavior would only concern newly
> written code that explicitly wants to take advantage of this feature.
>
> A few examples using functions (the same would apply to class methods,
> callbacks, closures, etc.) :
>
>      function foo (void) {}
>      foo(42); // warning: foo() expects exactly 0 arguments, 1 given
>
>      function bar ($a, $b, void) {}
>      bar(1, 2, 3); // warning: bar() expects exactly 2 arguments, 3 given
>
>      function baz ($a, $b=3Dnull, void) {}
>      baz(1, 2, 3); // warning: baz() expects at most 2 arguments, 3 given
>
> I have no knowledge of the PHP internals: would that be feasible without
> breaking things? And, as importantly, would it be a welcome change?
>
> Cheers,
>
> --
> Pablo

Hi Pablo,

I like this concept, but instead of introducing a new syntax, have you
considered leveraging attributes in the same way that PHP 8.3
introduced #[Override]?

#[Nonvariadic]
function foo () {}
foo(42); // warning: foo() expects exactly 0 arguments, 1 given

I think the intent would be clearer and it would avoid introducing a new sy=
ntax.

- Mark