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Date: Fri, 25 Oct 2019 12:27:06 +0200
Message-ID: <CAH0Uv3FtYCv03tg=jV=ch4+UTVOTuCCOyCNg6qhPVfqja5djpA@mail.gmail.com>
To: Rowan Tommins <rowan.collins@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] [RFC] anti-coalescing-operator
From: andreas@dqxtech.net (Andreas Hennings)

On Fri, 25 Oct 2019 at 12:21, Rowan Tommins <rowan.collins@gmail.com> wrote:
>
> On Thu, 24 Oct 2019 at 22:20, Kosit Supanyo <webdevxp.com@gmail.com> wrote:
>
> > But I think this functionality should be of something like pipeline
> > operator:
> >
> > // send tmp variable to the next expression unconditionally
> > $ret = $_SERVER['fname'] |>  $user->setName($$);
> > // send tmp variable to the next expression only when $_SERVER['fname'] is
> > set.
> > $ret = $_SERVER['fname'] ?|>  $user->setName($$);
> >
> > Also the syntax like above will be consistent with the proposed
> > safe-navigation operators.
> >
>
>
> I really like this idea, and it actually makes the pipeline operator itself
> feel more useful, too.
>
> Imagine this chain, where not only might the variable not be set, but it
> might not match a user, or the user might have no name:
>
> $upperCaseUserName = $_GET['user_id'] ?|> User::getById($$) ?-> getName()
> ?|> strtoupper($$);
>
> As well as not needing to repeat the expression each time, as you would
> with an "anti-coalesce", "null-safe chain" feels a clearer reading of the
> intent here than "if not unset".

I like this.
It is a bit like a temporary local variable.

One limitation is that you only have one such pipe value at a time.
E.g. it would not cover this:

return isset($a, $b) ? foo($a, $b) : null;

or any nested parameters like foo(bar(baz())) where any intermediate
value could be null.