Re: [RFC] Data Classes

> Rob Landers <rob@bottled.codes> hat am 23.11.2024 14:11 CET geschrieben: > > > Hello internals, > > Born from the Records RFC (https://wiki.php.net/rfc/records) discussion, I would like to > introduce to you a competing RFC: Data Classes (https://wiki.php.net/rfc/dataclass). > > This adds a new class modifier: data. This modifier drastically changes how classes work, > making them comparable by value instead of reference, and any mutations behave more like arrays than > objects (by vale). If desired, it can be combined with other modifiers, such as readonly, to enforce > immutability. > > I've been playing with this feature for a few days now, and it is surprisingly intuitive > to use. There is a (mostly) working implementation available on GitHub > (https://github.com/php/php-src/pull/16904) if you want to have a go at it. > > Example: > > data class UserId { public function __construct(public int $id) {} } > > $user = new UserId(12); > // later > $admin = new UserId(12); > if ($admin === $user) { // do something } // true > > Data classes are true value objects, with full copy-on-write optimizations: > > data class Point { > public function __construct(public int $x, public int $y) {} > public function add(Point $other): Point { > // illustrating value semantics, no copy yet > $previous = $this; > // a copy happens on the next line > $this->x = $this->x + $other->x; > $this->y = $this->y + $other->y; > assert($this !== $previous); // passes > return $this; > } > } > > I think this would be an amazing addition to PHP. > > Sincerely, > > — Rob > Thanks for the rfc! From userland perspective I would prefer to have the cloning more explicitly, e.g. return clone $this($this->x + $other->x, $this->y + $other->y); or return clone $this(x: $this->x + $other->x); // clone with y unchanged Best Regards Thomas