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Date: Tue, 26 Nov 2013 19:08:05 +0100
Message-ID: <CACQesk5fTF=Mjnmhm9A8dqtcLWQ-oqSRq2jdTb+qzJBpWb5mZA@mail.gmail.com>
To: Philip Sturgeon <pjsturgeon@gmail.com>
Cc: Paul Dragoonis <dragoonis@gmail.com>, Chris London <me@chrislondon.co>, 
	Mats Lindh <mats.lindh@gmail.com>, "internals@lists.php.net" <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c26b26e5c70104ec185d70
Subject: Re: [PHP-DEV] [Proposal] Modification to ?: functionality
From: colder@php.net (Etienne Kneuss)

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On Tue, Nov 26, 2013 at 6:57 PM, Philip Sturgeon <pjsturgeon@gmail.com>wrote:

> On Tue, Nov 26, 2013 at 12:41 PM, Paul Dragoonis <dragoonis@gmail.com>
> wrote:
> > On Tue, Nov 26, 2013 at 4:58 PM, Chris London <me@chrislondon.co> wrote:
> >
> >> On Tue, Nov 26, 2013 at 8:15 AM, Mats Lindh <mats.lindh@gmail.com>
> wrote:
> >>
> >> > On Tue, Nov 26, 2013 at 3:43 PM, Chris London <me@chrislondon.co>
> wrote:
> >> >
> >> >> I believe these two statements are functionally equivalent:
> >> >>
> >> >> $foo = $foo ? $foo : 'default';
> >> >>
> >> >> $foo = $foo ?: 'default';
> >> >>
> >> >
> >> > They are.
> >> >
> >> >
> >> > I would like to change it so it also checks for isset() so I propose
> the
> >> >> following would be functionally equivalent:
> >> >>
> >> >> $foo = isset($foo) && $foo ? $foo : 'default';
> >> >>
> >> >> $foo = $foo ?: 'default';
> >> >>
> >>
> >
> > We can't change the behaviour of ?: that ship has already sailed, we'll
> > just be hurting existing codebases on upgrading and more user education
> is
> > required to understand non-visual changes in syntax like this, lets try
> to
> > learn from our mistakes by not changing 'behaviour' anymore.
> >
> > An alternative syntax that is similar and not ugly would be good since
> the
> > ?: behaviour was broken from the start since you still need to run
> isset()
> > before running ?: which was the problem we tried to solve in the first
> > place but it just didn't happen.
> >
> > I don't like the @ symbol it's too different from what's already there on
> > the ternary logic.
> >
> > Proposal:   $foo = $arr['value'] ?:: "";
> >
> > Thoughts?
> >
> >>
> >> > The would break the assumption that a reference to an uninitialized
> value
> >> > would generate a notice, unless explicitly handled in the logic.
> >> >
> >> > While I also would like to have something similar to ?: to handle
> default
> >> > values for array keys, etc., this would change a fundamental
> assumption
> >> > that as been in place for many years now. I'm not sure if that's a BC
> >> break
> >> > that would be acceptable this late. An alternative operator may be
> more
> >> > suitable.
> >> >
> >>
> >> What do you think about using:
> >>
> >> $foo = $foo @: 'default';
> >>
> >> and possibly
> >>
> >> $foo @= 'default';
> >>
> >>
> >>
> >> >
> >> > The change proposed has also been discussed several times since the
> >> > implementation of ?:. See the ifsetor-RFC:
> >> >
> >> > https://wiki.php.net/rfc/ifsetor
> >> >
> >> > It also contains links to the discussion around the feature back then.
> >> >
> >> > --mats
> >> >
> >>
>
> This seems like a cracking time to suggest:
>
>    $x ||= $y;
>
> The difference? Anything left of the ? SHOULD fail if it is not set,
> because you are using it in a condition which is dangerous and odd for
> other types of condition, but adding in this new syntax (similar to
> Ruby) would essentially evaluate to this:


>    empty($x) ? $y : $x;
>
> This gives keeps the behavior of ternary operators working in the same
> way, but adds what we want: the ability to nicely set defaults for
> variables and array keys that may not be set.
>

To me this reads as $x = $x || $y like all the <OP>= binary operators. So
it would definitely feel weird to use that syntax for something else...


>
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>
>


-- 
Etienne Kneuss
http://www.colder.ch

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