Bound-Erased Generic Types
This RFC adds generic type syntax to PHP. Classes, interfaces, traits, functions, methods, closures, and arrow functions can declare type parameters; those parameters carry bounds, defaults, and variance markers; type arguments may be supplied at use sites and at call sites via turbofish.
final readonly class Pair<+L, +R> { public function __construct( public L $left, public R $right, ) {} public function swap(): Pair<R, L> { return new Pair($this->right, $this->left); } } final readonly class Box<+T> { public function __construct( public T $value, ) {} public function map<U>(callable $fn): Box<U> { return new Box(($fn)($this->value)); } public function zip<O>(O $value): Box<Pair<T, O>> { return new Box(new Pair($this->value, $value)); } } function identity<T>(T $value): T { return $value; } $greeting = new Box::<string>("hello, world"); $paired = $greeting->zip::<int>(42); $swapped = $paired->value->swap(); $result = identity::<Pair<int, string>>($swapped);
I've been writing about this for years. If we ever want generics in PHP, this is the way.
I don't often use generic definitions in docblocks today, but when I do, it's a mess. I think this RFC is the right move at the right time, and cost (both runtime and syntax) appears zero to minimal at best. It'd be really great to see generics land in PHP. It's been a long time coming.
Generics are one of the most requested feature since PHP met the OOP paradigm and for me, this will step to set the boundaries to its OOP complete adherence.
We will be able to describe complex classes or dynamically typed ones, increase readability and move type hinting away from comments.
This should be native to the language.
Along with the host of all previously mentioned advantages, I find that this could open the door for much more in-depth compiler analysis leading to better performance in the future!
Generics and Async are two of the fundamental pillars of modern PHP, and we need to achieve them.
finally, please let it pass
I'm more in the doubting camp, but there is only YES or NO vote available.
I'm really concerned about the cognitive load while reading the code, it adds complexity, PHP's selling point was its simplicity, features like Aviz, and other make it harder and harder to read and understand quickly.
So, be careful what you wish for)
If you like it or not, generics are already used in the wild. Having a standardized syntax is, in my opinion, a no-brainer.
This RFC chooses its scope carefully, providing some safety where it is easy to do so, while delegating the rest to static analyzers and keeping backwards compatibility. With this, the different static analyzers can finally agree on certain behaviors, because they are part of the language.
Having the generic type information available through reflection opens up exciting new possibilities.
Keeping the doors open for future expansion is another very important win.
TL;DR: The RFC is very pragmatic given the design of PHP. Provides very solid foundation upon which to build that was missing and asked for a decade.
This would easily be one of the best features of modern PHP. Nobrainer.
Looking forward to this feature landing in PHP 8.6.
Long awaited.
Yes please! This would remove a lot of docblocks everywhere. Huge PHPStan user here.
Check out another RFCs
Interface Default Methods improves backwards compatibility when changing interfaces, but also add a way to have multi-inheritance in PHP.
This RFC proposes a way to have multi-line short closures — closures that don't need explicit use statements, but can still have multiple lines and a return statement.