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To: Mark Randall <marandall@php.net>, "internals@lists.php.net"
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Thread-Topic: [PHP-DEV] The @@ is terrible, are we sure we're OK with it?
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Date: Thu, 23 Jul 2020 14:09:16 +0000
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Subject: Re: [PHP-DEV] The @@ is terrible, are we sure we're OK with it?
From: theodorejb@outlook.com (Theodore Brown)

On Thu, July 23 2020 at 1:26 AM Mark Randall <marandall@php.net> wrote:=0A=
=0A=
> On 23/07/2020 02:00, Sara Golemon wrote:=0A=
> > Regards the vote; I don't believe that @@ has been proven unworkable,=
=0A=
> > however if I'm wrong about that, then the second choice selection from =
the=0A=
> > last vote would obviously take precedence.=0A=
>=0A=
> I don't believe the concern is that we have something unworkable sitting=
=0A=
> in front of us right now, after all if that were the case we would not=0A=
> be needing to have this conversation as the RFC would already have been=
=0A=
> rendered void.=0A=
> =0A=
> What we do have, is a deep sense of unease that we collectively made the=
=0A=
> wrong decision, based on, in part, incomplete information.=0A=
> =0A=
> While the initial block to @@ has been remedied by a larger=0A=
> language-level change, that the problem existed at all provided a clear=
=0A=
> example of the widely unforeseen challenges associated with the @@=0A=
> syntax and its lack of closing tags, and focused renewed attention on=0A=
> long-term consequences which where perhaps not given enough=0A=
> consideration during the vote.=0A=
> =0A=
> There has been one occurrence already, there will likely be more in the=
=0A=
> future. But what specifically will they be and how severe? We likely=0A=
> will not know until they happen.=0A=
=0A=
Hi Mark,=0A=
=0A=
I don't agree that there "will likely be more in the future". When I=0A=
asked Nikita if he could think of any example that would end up being=0A=
a problem, the only one he listed was a infinite parser lookahead=0A=
requirement if a) attributes were allowed on statements and b)=0A=
generics were implemented with curly braces instead of angle brackets.=0A=
=0A=
He noted that "it's unlikely we'd actually do that" and ended his=0A=
email by saying "it is more likely than not, that we will not=0A=
encounter any issues of that nature." [1]=0A=
=0A=
The @ attribute syntax has been used in other C family languages for=0A=
years, and to my knowledge hasn't caused any problems in practice.=0A=
=0A=
It is actually the <<>> variant that is more likely to back us into a=0A=
corner when it comes to future syntax like nested attributes (the RFC=0A=
authors considered it to cross a line of unacceptable ugliness,=0A=
and the alternative `new Attribute` syntax has technical problems).=0A=
This may be one reason Hack is moving away from it to @.=0A=
=0A=
> But what we can say with reasonable confidence is we have an option=0A=
> on the table that is technically superior=0A=
=0A=
I don't agree that #[] is technically superior. The implementation is=0A=
virtually identical. The main practical difference is that hash=0A=
comments could no longer start with a [ character, which would be=0A=
surprising behavior and a larger BC break (there's definitely code in=0A=
the wild using this right now).=0A=
=0A=
If you have a concrete example of syntax that is *likely* to cause a=0A=
problem with @@, please share it. From my perspective, @@ is closest=0A=
to the syntax used by the majority of C family languages for=0A=
attributes, and thus is *least likely* to present future challenges.=0A=
=0A=
Best regards,  =0A=
Theodore=0A=
=0A=
[1]: https://externals.io/message/110568#111053=