[8.x] Allow for named arguments via dispatchable trait

[sleicester]

I've had a situation where it would be nice to use named arguments in dispatching a job to the queue as it allows me to leave out arguments:

RegisterResponse::dispatch(
    uuid: $uuid,
    question: $request->question,
    answer: $request->answer,
    referer: $request->input('referer', $request->headers->get('referer'))
);

Unfortunately this will now work as dispatch, dispatchSync and dispatchAfterRequest don't receive any arguments.

Obviously it's easy enough to go about this a different way:

dispatch(new RegisterResponse(
    question: $request->question,
    answer: $request->answer,
));

Are there any consequences to these simple changes that I'm not foreseeing?

[GrahamCampbell]

I don't think we should actually support named arguments, here. Laravel doesn't support named arguments, so it seems wrong to allow it here. If anything, we could throw an exception saying it's not supported.

[sleicester]

Thanks @GrahamCampbell, I did think it could open a can of worms as there are more likely other places that aren't so simple to change, and probably best dealt with when the minimum PHP version is bumped to 8.

Although, if Laravel would want to support named arguments in the future, then perhaps it's good to start looking at small non-breaking changes now?

[GrahamCampbell]

I can't see Laravel ever wanting to support them, tbh.

[lassemettovaara]

I don't think we should actually support named arguments, here. Laravel doesn't support named arguments, so it seems wrong to allow it here. If anything, we could throw an exception saying it's not supported.

It's certainly fine for Laravel not to actively support named arguments, but to me this feels like a weird place to explicitly disallow it since it's just proxying user defined arguments to user defined methods.

Also: events sometimes accept named arguments, like:

use Illuminate\Foundation\Events\Dispatchable;

class Foo
{
    use Dispatchable;

    public function __construct(
        public string $foo,
        public bool $bar,
    ) {
        var_dump($this->foo, $this->bar);
    }
}

Foo::dispatchIf(true, foo: 'some string', bar: false);
Foo::dispatchUnless(false, bar: true, foo: 'some other string');

This already works fine, since dispatchIf and dispatchUnless use variadics instead of func_get_args.

Edit: the same obviously goes for jobs.