Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:94659
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: softfail (pb1.pair.com: domain golemon.com does not designate 209.85.223.182 as permitted sender)
MIME-Version: 1.0
Sender: php@golemon.com
In-Reply-To: <b4fe9f42-3cf0-26d9-60db-782a4ac3d125@gmail.com>
References: <CAESVnVoBrtfWGF-Be+uXWwLNO3=JzuLBXyhW0Dpo-NvoskofQw@mail.gmail.com>
 <71557808-5718-0406-3df9-830bc2e03006@gmail.com> <CAESVnVosKc=-yfF3oAP3Oo9Z4F9_Fcv9Nu12S6SOPWykO6ZX5w@mail.gmail.com>
 <5024e8b2-4a4d-4a12-99f3-a539c9930337@gmail.com> <CAESVnVp9JeHjODR6vTiYAOsOOs7dw6D95zgxQ3yVhCvKGDr7xw@mail.gmail.com>
 <b4fe9f42-3cf0-26d9-60db-782a4ac3d125@gmail.com>
Date: Sat, 23 Jul 2016 13:49:47 -0700
Message-ID: <CAESVnVqoy=sPZmBbKi-XH8+0W_tEjfhPFp_wUNto4v+QcfLSJQ@mail.gmail.com>
To: Rowan Collins <rowan.collins@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] Pipe Operator v2
From: pollita@php.net (Sara Golemon)

On Sat, Jul 23, 2016 at 8:15 AM, Rowan Collins <rowan.collins@gmail.com> wrote:
> Glad it makes sense. :) I realise "return $$" would have to have some
> special handling, but it would feel more natural to me. I guess the only
> concern is what happens when a pipeline has a return terminal and is used in
> expression context:
>
> $foo = bar() |> baz($$) |> return $$;
> // theoretically translates to this invalid PHP:
> $foo = return baz(bar());
>
> I'm not sure how easily the compiler would be able to pick up that that's an
> illegal construction.
>
Right, which is where I'm hesitant to go down that road.

> I was going to say that "yield" would be worth considering at the same time,
> but presumably that's already legal, because yield can appear as an
> expression (to receive variables sent into a co-routine).
>
Yep.  Perfectly valid as-is, so a non-issue.

> It's a shame neither "echo" nor "print" is useful for getting $$ out to
> screen and leaving it unchanged (echo doesn't work in expression context at
> all; print doesn't have a useful return value).
>
Yeah, those pegs really don't fit into this hole...

> It might be worth coming up with some examples to add to the RFC where $$ is
> used in an expression other than a function call, because I wasn't entirely
> sure when I read it if that was even allowed. It might also clear up some of
> the confusion around this being anything to do with OO.
>
> Off the top of my head, how about some maths:
>
> $foo * $bar
>     |> 2 ** $$
>     |> sin($$ + 1)
>     |> $$ / 20
>     |> $result = $$;
>
> Compiles to:
>
> $result = sin((2 ** ($foo * $bar)) + 1) / 20;
>
> Or:
>
> $temp = $foo * $bar;
> $temp = 2 ** $temp;
> $temp = sin($temp + 1);
> $result = $temp / 20;
>
Fair point, I took those as a given, but they should be added. (And
yes, they're valid).

-Sara