Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:126705
Feedback-ID: ifab94697:Fastmail
Precedence: bulk
MIME-Version: 1.0
Date: Mon, 10 Mar 2025 23:59:49 +0100
To: internals@lists.php.net
Message-ID: <11584084-56ae-4775-8ea6-05b09eefca17@app.fastmail.com>
In-Reply-To: 
 <CALaXqqRWL8ygMGoA5xnMtt7w6rE-5WJJZ5P9oiO3vHgqvod=Fw@mail.gmail.com>
References: 
 <CALaXqqRWL8ygMGoA5xnMtt7w6rE-5WJJZ5P9oiO3vHgqvod=Fw@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Never parameters
Content-Type: multipart/alternative;
 boundary=bc1f03e3ec804400b0de00faee3397ce
From: rob@bottled.codes ("Rob Landers")

--bc1f03e3ec804400b0de00faee3397ce
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable

On Mon, Mar 10, 2025, at 20:05, Daniel Scherzer wrote:
> Hi internals,
>=20
> I'd like to start discussion on a new RFC about allowing `never` for p=
arameter types when declaring a method.
>=20
> * RFC: https://wiki.php.net/rfc/never-parameters-v2
> * Implementation: https://github.com/php/php-src/pull/18016
>=20
> -Daniel

Hey Daniel,

This looks interesting. I'm not sure that I like "never" as a parameter =
type and while it "technically" doesn't violate LSP, it seems like a bac=
kdoor to doing just that:

abstract class Point {
  function add(never $other);
  function subtract(never $other);
}

class Vector2 extends Point {
  public function add(Banana $other) {}
  public function subtract(Football $other) {}
}

There's basically only a gentleman's agreement that a subclass will impl=
ement things in a way that makes sense. I would also personally prefer a=
ssociated types:

abstract class Point {
  public type OtherPoint;
  public function add(OtherPoint $other);
  pubic function subtract(OtherPoint $other);
}

This at least lets you ensure the "other point" is the same type in both=
 functions, though personally, I'd rather just have generics.

=E2=80=94 Rob
--bc1f03e3ec804400b0de00faee3397ce
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Mon, Mar 10,=
 2025, at 20:05, Daniel Scherzer wrote:<br></div><blockquote type=3D"cit=
e" id=3D"qt" style=3D""><div dir=3D"ltr"><div>Hi internals,<br></div><di=
v><br></div><div>I'd like to start discussion on a new RFC about allowin=
g `never` for parameter types when declaring a method.<br></div><div><br=
></div><div>* RFC:&nbsp;<a href=3D"https://wiki.php.net/rfc/never-parame=
ters-v2">https://wiki.php.net/rfc/never-parameters-v2</a><br></div><div>=
* Implementation:&nbsp;<a href=3D"https://github.com/php/php-src/pull/18=
016">https://github.com/php/php-src/pull/18016</a><br></div><div><br></d=
iv><div>-Daniel<br></div></div></blockquote><div><br></div><div>Hey Dani=
el,<br></div><div><br></div><div>This looks interesting. I'm not sure th=
at I like "never" as a parameter type and while it "technically" doesn't=
 violate LSP, it seems like a backdoor to doing just that:<br></div><div=
><br></div><div>abstract class Point {<br></div><div>&nbsp; function add=
(never $other);<br></div><div>&nbsp; function subtract(never $other);</d=
iv><div>}</div><div><br></div><div>class Vector2 extends Point {<br></di=
v><div>&nbsp; public function add(Banana $other) {}<br></div><div>&nbsp;=
 public function subtract(Football $other) {}</div><div>}<br></div><div>=
<br></div><div>There's basically only a gentleman's agreement that a sub=
class will implement things in a way that makes sense. I would also pers=
onally prefer associated types:<br></div><div><br></div><div>abstract cl=
ass Point {<br></div><div>&nbsp; public type OtherPoint;<br></div><div>&=
nbsp; public function add(OtherPoint $other);<br></div><div>&nbsp; pubic=
 function subtract(OtherPoint $other);<br></div><div>}<br></div><div><br=
></div><div>This at least lets you ensure the "other point" is the same =
type in both functions, though personally, I'd rather just have generics=
.<br></div><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob<br></di=
v></body></html>
--bc1f03e3ec804400b0de00faee3397ce--