Re: Re: RFC: short and inner classes

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, >> >> I'd like to introduce my RFC for discussion: >> https://wiki.php.net/rfc/short-and-inner-classes >> >> 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 related to different/new/incorrect error >> messages being generated. However, the core functionality exists to take for a test ride. >> >> So, what do I mean by "unprecedented amount of control"? With this change, you >> can declare an inner class as private or protected, preventing its usage outside of the outer class: >> >> class User { >> private class Id {} >> >> public function __construct(public self::Id $id) {} >> } >> >> In the above example, the class User is impossible to >> construct even though it has a public constructor (except through reflection) because User::Id is >> private; User::Id cannot be instantiated, used as a type hint, or even via >> instanceof outside of the User class itself. This example 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. >> >> As a number of inner classes will probably be used as DTOs, the RFC introduces a >> "short syntax" for declaring classes, which enhances expressiveness, even allowing the >> usage of traits, all in a single line: >> >> // declare a readonly Point, that implements Vector2 and uses the Evolvable trait >> readonly class Point(public int $x, public int $y) implements Vector2 use Evolvable; >> >> When combined with inner classes, it looks something like this: >> >> class Pixel { >> public readonly class Point(public int $x, public int $y) implements Vector2 use >> Evolvable; >> } >> >> // Create a new pixel point with property $x and $y set to 0 >> $p = new Pixel::Point(0, 0); >> >> There are far more details in the RFC itself, so please check it out. I'm quite >> excited to hear your thoughts! >> >> — Rob >> >> PS. I know I tend to rush into things, but I want to make it clear that I'm not >> rushing this -- I've learned from my mistakes (thank you to those who have given me advice). >> I'm going to do this right. >> >> > > Hello internals, > > I've made some major updates to the text of the RFC to clarify behaviors and revisited the > implementation (which is still 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: > > - 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. > > 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 itself. > > — Rob For those who are interested, I've opened the PR that enables this feature: https://github.com/php/php-src/pull/18069 — Rob