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Date: Fri, 15 Mar 2019 11:02:38 +0100
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To: Mathieu Rochette <mathieu@rochette.cc>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Arrow functions / short closures
From: nikita.ppv@gmail.com (Nikita Popov)

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On Thu, Mar 14, 2019 at 3:04 PM Mathieu Rochette <mathieu@rochette.cc>
wrote:

>
> Hi,
>
> it's nice to see this going on again :)
>
> while reading the rfc I was wondering, why do we need the "static"
> keyword, couldn't static function be detected automatically ?
>

I've added a note regarding this in
https://wiki.php.net/rfc/arrow_functions_v2#this_binding_and_static_arrow_f=
unctions.
The problem is that in PHP we cannot actually reliably detect whether or
not a closure uses $this. Sure -- we can see literal $this uses, but some
of them are implicit:

fn() =3D> Foo::bar() can make use of $this if $this is scope-compatible wit=
h
Foo. fn() =3D> call_user_func('Foo::bar') can as well. fn() =3D> $a($b) can=
 as
well, if it so happens that $a =3D 'call_user_func' and $b =3D 'Foo::bar'. =
The
result is that we cannot reliably detect whether $this is used or not -- we
can only make a conservative analysis that may sometimes bind $this even
though it's not needed. In which case I would prefer going with the more
predictable behavior of always binding $this, and using "static" in the
rare cases where someone really cares about this.


> I guess this apply to the existing closure syntax as well so to get more
> on this topic I'll share my preferences on the syntax: I like the =3D=3D>=
 or ~>
> version because it also allow to drop the parenthesis when there is only
> one argument and it's closer to what I'm used to in javascript
>
> I wouldn't mind having the rust syntax too but yeah, it would feel a bit
> odd in PHP
>
>
> thank you for your work on this !
>
> Nikita Popov =E2=80=93 Wed, 13. March 2019 16:57
> > Hi internals,
> >
> > Motivated by the recent list comprehensions RFC, I think it's time we
> took
> > another look at short closures:
> >
> > wiki.php.net/rfc/arrow_functions_v2
> >
> > This is based on a previous (withdrawn) proposal by Levi & Bob. It uses
> the
> > syntax
> >
> > fn($x) =3D> $x * $multiplier
> >
> > and implicit by-value variable binding. This example is roughly
> equivalent
> > to:
> >
> > function($x) use($multiplier) { return $x * $multiplier; }
> >
> > The RFC contains a detailed discussion of syntax choices and binding
> modes.
> >
> > Regards,
> > Nikita
>

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