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To: Derick Rethans <derick@php.net>, PHP Developers Mailing List
	<internals@lists.php.net>
Thread-Topic: [PHP-DEV] [VOTE] Shorter Attribute Syntax Change
Thread-Index: AQHWbvIF7KrSF3HLUE2WaV22ixIGaKk2RucY
Date: Thu, 13 Aug 2020 17:21:55 +0000
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Subject: Re: [PHP-DEV] [VOTE] Shorter Attribute Syntax Change
From: tysonandre775@hotmail.com (tyson andre)

Hi internals,=0A=
=0A=
One thing I hadn't thought of=A0before was how this would interact with par=
ameters (with or without constructor property promotion).=0A=
Many coding styles would end up putting annotations on the same line for pa=
rameters (in addition to closures)=0A=
E.g. I've commonly done that and seen that done in Java:=0A=
https://stackoverflow.com/questions/30237266/java-parameter-annotations=0A=
=0A=
```=0A=
class X {=0A=
    public function __construct(=0A=
        @@MyImmutable public bool $x,=0A=
        private bool $flag =3D false,=0A=
    ) {}=0A=
    public function __construct(=0A=
        @[MyImmutable] public bool $x,=0A=
        private bool $flag =3D false,=0A=
    ) {}=0A=
    // This comments out the first parameter entirely in php7, silently lea=
ding to different behavior in php 7=0A=
    public function __construct(=0A=
        #[MyImmutable] public bool $x,=0A=
        private bool $flag =3D false,=0A=
    ) {}=0A=
}=0A=
```=0A=
=0A=
As Theodore said, this RFC doesn't include enough examples to give a compre=
hensive understanding of how #[] would be implemented and what the implemen=
tation implies, which the original shorter attribute syntax did https://wik=
i.php.net/rfc/shorter_attribute_syntax#alternative_syntax=0A=
=0A=
(e.g. this gets parsed as `$f1 =3D $f2 =3D $object =3D new foo();` in php 7=
 and would not warn with your patch (from the mailing list) in php8. No pat=
ch for #[Attr] is linked in the RFC document.)=0A=
=0A=
```=0A=
$f1 =3D #[ExampleAttribute] function () {};=0A=
 =0A=
$f2 =3D #[ExampleAttribute] fn() =3D> 1;=0A=
=0A=
$object =3D new #[ExampleAttribute] class () {};=0A=
foo();=0A=
```=0A=
=0A=
Even if the RFC was amended after the vote was started,=0A=
I don't think that people who had already voted would see the changes or re=
ad all of the numerous emails in this thread.=0A=
=0A=
> Changes lexing of remaining tokens indicates that a newly introduced toke=
n changes the behaviour of existing tokens.=0A=
> In the example of `#[` the occurance of a # would have previously always =
signified a comment, but that now changes to become an attribute instead wh=
en followed by `[`.=0A=
=0A=
That's similar to saying that the `??` token would have previously indicate=
d a `?` for a nullable type/ternary, but would change to become a null coal=
escing operator when followed by `?`.=0A=
It understates/omits mentions of the changes to lexing this can cause, whic=
h I mentioned in https://externals.io/message/111218#111239=0A=
=0A=
```=0A=
?php=0A=
// This example echoes the rest of the source code in php 7=0A=
// and echoes "Test" in php 8.=0A=
#[DeprecationReason('reason: <https://some-website/reason?>')]=0A=
function main() {}=0A=
const APP_SECRET =3D 'app-secret';=0A=
echo "Test\n";=0A=
```=0A=
=0A=
```=0A=
// yields false in php 7, yields a function in php 8=0A=
function generator() {=0A=
    yield #[MyCustomAttribute('=0A=
        false;=0A=
        // ']function() {};=0A=
}=0A=
```=0A=
=0A=
Regards,=0A=
- Tyson=