Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:126761
Feedback-ID: ifab94697:Fastmail
Precedence: bulk
MIME-Version: 1.0
Date: Fri, 14 Mar 2025 19:46:22 +0100
To: internals@lists.php.net
Message-ID: <80a72934-fada-47a7-b35b-59a1c8704097@app.fastmail.com>
In-Reply-To: <2935d0e2-ddc4-447c-ab37-c9b7337b8b60@app.fastmail.com>
References: <aae32397-0567-417f-adbe-6b663d5c49ae@app.fastmail.com>
 <2935d0e2-ddc4-447c-ab37-c9b7337b8b60@app.fastmail.com>
Subject: Re: [PHP-DEV] Re: RFC: short and inner classes
Content-Type: multipart/alternative;
 boundary=1ae25b4bb160418d8d482a5b3b72b6e2
From: rob@bottled.codes ("Rob Landers")

--1ae25b4bb160418d8d482a5b3b72b6e2
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable

On Wed, Mar 12, 2025, at 11:10, Rob Landers wrote:
> On Thu, Mar 6, 2025, at 00:11, Rob Landers wrote:
>> Hello PHP Internals,
>>=20
>> I'd like to introduce my RFC for discussion: https://wiki.php.net/rfc=
/short-and-inner-classes
>>=20
>> This RFC defines a short class syntax as well as the ability to nest =
classes inside another class. This introduces an unprecedented amount of=
 control, flexibility, and expressiveness over how objects are used and =
instantiated in PHP. There is a PR (https://github.com/php/php-src/pull/=
17895) that implements this functionality -- all test failures are relat=
ed to different/new/incorrect error messages being generated. However, t=
he core functionality exists to take for a test ride.
>>=20
>> So, what do I mean by "unprecedented amount of control"? With this ch=
ange, you can declare an inner class as private or protected, preventing=
 its usage outside of the outer class:
>>=20
>> class User {
>>   private class Id {}
>>=20
>>   public function __construct(public self::Id $id) {}
>> }
>>=20
>> In the above example, the class `User` is impossible to construct eve=
n though it has a public constructor (except through reflection) because=
 User::Id is private; User::Id cannot be instantiated, used as a type hi=
nt, or even via `instanceof` outside of the User class itself. This exam=
ple isn't practical but demonstrates something that is nearly impossible=
 in previous versions of PHP, where all classes are essentially publicly=
 accessible from anywhere within the codebase.
>>=20
>> As a number of inner classes will probably be used as DTOs, the RFC i=
ntroduces a "short syntax" for declaring classes, which enhances express=
iveness, even allowing the usage of traits, all in a single line:
>>=20
>> // declare a readonly Point, that implements Vector2 and uses the Evo=
lvable trait
>> readonly class Point(public int $x, public int $y) implements Vector2=
 use Evolvable;
>>=20
>> When combined with inner classes, it looks something like this:
>>=20
>> class Pixel {
>>   public readonly class Point(public int $x, public int $y) implement=
s Vector2 use Evolvable;
>> }
>>=20
>> // Create a new pixel point with property $x and $y set to 0
>> $p =3D new Pixel::Point(0, 0);
>>=20
>> There are far more details in the RFC itself, so please check it out.=
 I'm quite excited to hear your thoughts!
>>=20
>> =E2=80=94 Rob
>>=20
>> PS. I know I tend to rush into things, but I want to make it clear th=
at I'm not rushing this -- I've learned from my mistakes (thank you to t=
hose who have given me advice). I'm going to do this right.
>>=20
>>=20
>=20
> Hello internals,
>=20
> I've made some major updates to the text of the RFC to clarify behavio=
rs and revisited the implementation (which is still under development, t=
hough I hope to have a draft by the end of this weekend). Here's a broad=
 overview of what has changed in inner classes:
>=20
> - Accessing inner classes is done via a new token: ":>" instead of "::=
".
> - Inner classes may now be infinitely nested.
> - Inner classes may be declared `abstract`.
> - Documented changes to ReflectionClass.
> - Usage of `static` to refer to inner classes is restricted to prevent=
 accidental violations of LSP.
>=20
> Otherwise, there are not any big changes, but a lot of time was spent =
clarifying behavior and expanding on the reasoning for those decisions i=
n the RFC itself.
>=20
> =E2=80=94 Rob

For those who are interested, I've opened the PR that enables this featu=
re: https://github.com/php/php-src/pull/18069

=E2=80=94 Rob
--1ae25b4bb160418d8d482a5b3b72b6e2
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html><html><head><title></title><style type=3D"text/css">=0Ap.=
MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Wed, Mar =
12, 2025, at 11:10, Rob Landers wrote:<br></div><blockquote type=3D"cite=
" id=3D"qt" style=3D""><div>On Thu, Mar 6, 2025, at 00:11, Rob Landers w=
rote:<br></div><blockquote type=3D"cite" id=3D"qt-qt" style=3D""><div>He=
llo PHP Internals,<br></div><div><br></div><div>I'd like to introduce my=
 RFC for discussion:&nbsp;<a href=3D"https://wiki.php.net/rfc/short-and-=
inner-classes">https://wiki.php.net/rfc/short-and-inner-classes</a><br><=
/div><div><br></div><div>This RFC defines a short class syntax as well a=
s the ability to nest classes inside another class. This introduces an u=
nprecedented amount of control, flexibility, and expressiveness over how=
 objects are used and instantiated in PHP. There is a PR (<a href=3D"htt=
ps://github.com/php/php-src/pull/17895">https://github.com/php/php-src/p=
ull/17895</a>) that implements this functionality -- all test failures a=
re related to different/new/incorrect error messages being generated. Ho=
wever, the core functionality exists to take for a test ride.<br></div><=
div><br></div><div>So, what do I mean by "unprecedented amount of contro=
l"? With this change, you can declare an inner class as private or prote=
cted, preventing its usage outside of the outer class:<br></div><div><br=
></div><div>class User {<br></div><div>&nbsp; private class Id {}<br></d=
iv><div><br></div><div>&nbsp; public function __construct(public self::I=
d $id) {}<br></div><div>}<br></div><div><br></div><div>In the above exam=
ple, the class `User` is impossible to construct even though it has a pu=
blic constructor (except through reflection) because User::Id is private=
; User::Id cannot be instantiated, used as a type hint, or even via `ins=
tanceof` outside of the User class itself. This example isn't practical =
but demonstrates something that is nearly impossible in previous version=
s of PHP, where all classes are essentially publicly accessible from any=
where within the codebase.<br></div><div><br></div><div>As a number of i=
nner classes will probably be used as DTOs, the RFC introduces a "short =
syntax" for declaring classes, which enhances expressiveness, even allow=
ing the usage of traits, all in a single line:<br></div><div><br></div><=
div>// declare a readonly Point, that implements Vector2 and uses the Ev=
olvable trait<br></div><div>readonly class Point(public int $x, public i=
nt $y) implements Vector2 use Evolvable;<br></div><div><br></div><div>Wh=
en combined with inner classes, it looks something like this:<br></div><=
div><br></div><div>class Pixel {<br></div><div>&nbsp; public readonly cl=
ass Point(public int $x, public int $y) implements Vector2 use Evolvable=
;<br></div><div>}<br></div><div><br></div><div>// Create a new pixel poi=
nt with property $x and $y set to 0<br></div><div>$p =3D new Pixel::Poin=
t(0, 0);<br></div><div><br></div><div>There are far more details in the =
RFC itself, so please check it out. I'm quite excited to hear your thoug=
hts!<br></div><div><br></div><div id=3D"qt-qt-sig121229152">=E2=80=94 Ro=
b<br></div><div id=3D"qt-qt-sig121229152"><br></div><div><div>PS. I know=
 I tend to rush into things, but I want to make it clear that I'm not ru=
shing this -- I've learned from my mistakes (thank you to those who have=
 given me advice). I'm going to do this right.<br></div><div><br></div><=
/div><div><br></div></blockquote><div><br></div><div>Hello internals,<br=
></div><div><br></div><div>I've made some major updates to the text of t=
he RFC to clarify behaviors and revisited the implementation (which is s=
till under development, though I hope to have a draft by the end of this=
 weekend). Here's a broad overview of what has changed in inner classes:=
<br></div><div><br></div><div>- Accessing inner classes is done via a ne=
w token: ":&gt;" instead of "::".<br></div><div>- Inner classes may now =
be infinitely nested.<br></div><div>- Inner classes may be declared `abs=
tract`.<br></div><div>- Documented changes to ReflectionClass.<br></div>=
<div>- Usage of `static` to refer to inner classes is restricted to prev=
ent accidental violations of LSP.<br></div><div><br></div><div>Otherwise=
, there are not any big changes, but a lot of time was spent clarifying =
behavior and expanding on the reasoning for those decisions in the RFC i=
tself.<br></div><div><br></div><div id=3D"qt-sig121229152">=E2=80=94 Rob=
<br></div></blockquote><div><br></div><div>For those who are interested,=
 I've opened the PR that enables this feature:&nbsp;<a href=3D"https://g=
ithub.com/php/php-src/pull/18069">https://github.com/php/php-src/pull/18=
069</a><br></div><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob<b=
r></div></body></html>
--1ae25b4bb160418d8d482a5b3b72b6e2--