Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:51838
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.212.42 as permitted sender)
DomainKey-Status: bad
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:in-reply-to:references:date:message-id:subject:from:to
         :cc:content-type;
        b=g4diRIsumRAw008cw7NKXheac4EUpRTmRbYWfq6EDScpaZhVuiVDWvunXv8dZTYjNK
         VhAUn1UhYQArKnQppPvdeqmXRN9AHtrfNTDId3SeB7fSA8YdASyVZy6JJb+YiyVM/4Uq
         2tUmI1Oxil7GnZb0X7IqgPqBnIpCk5iGogxcs=
MIME-Version: 1.0
In-Reply-To: <BANLkTim6ZBWw66rzx_gSvWc9E45EZx2_gw@mail.gmail.com>
References: <AANLkTiknomAsTrsZ140rWs6CwxJP3UYGUokQbERhDiRp@mail.gmail.com>
	<4D950434.3060704@yahoo.com.au>
	<BANLkTinzb5xiD8j7ZXB+cT4EBZY3DF6BYQ@mail.gmail.com>
	<4D9E0543.1080600@lerdorf.com>
	<69.82.36433.EC33E9D4@pb1.pair.com>
	<4D9E34C4.5000406@lerdorf.com>
	<4D9E429B.20503@sugarcrm.com>
	<4D9E96B6.6060401@lerdorf.com>
	<BANLkTi=LvYLaOoGgrzrWfYbQ+t9Wzv_XeQ@mail.gmail.com>
	<BANLkTim6ZBWw66rzx_gSvWc9E45EZx2_gw@mail.gmail.com>
Date: Fri, 8 Apr 2011 15:19:37 +0200
Message-ID: <BANLkTinxG6FtOqa8KzmvgTT1EFfM-6prow@mail.gmail.com>
To: Hannes Landeholm <landeholm@gmail.com>
Cc: Adam Richardson <simpleshot@gmail.com>, internals@lists.php.net
Content-Type: text/plain; charset=ISO-8859-1
Subject: Re: [PHP-DEV] Implicit isset/isempty check on short-ternary operator
From: rumi.kg@gmail.com (Rune Kaagaard)

Dear Internals

I'm very happy that this is getting some attention again. Please allow
me to give my 2 cents too. The text below can also be seen nicely
formatted at https://gist.github.com/909711.

## Intro ##

Isset and IsNotEmpty operators have for sure been a hot topic for several years
now and in my opinion rightly so. The non-DRY style of:

    $my_array['my_long_boring_key'] = !empty($my_array['my_long_boring_key'])
                  ? $my_array['my_long_boring_key'] : 'Default value';
    $my_array['my_long_boring_key'] = isset($my_array['my_long_boring_key'])
                  ? $my_array['my_long_boring_key'] : 'Default value';

is a true day-to-day hassle and addressing this annoyance would be a
big win for
the PHP community as a whole. As PHP has two keywords `isset` and `empty` that
can check for a non existing variable without throwing errors I think there
should exist two assignment/ternary operators who mirror those.

I have been thinking [1] about the same problem for my meta language Snow and
also ended up using `??` as an isset operator.

## Proposal ##
I propose that two new operators `??` (IssetOperator) and `?!`
(NotEmptyOperator) are added. `??` mirrors `isset` and `?!` mirrors `!empty`.
They are chainable ad nauseum but not with each other.

They would work like this:

### Example 1 : Ternary shortcut ###
Old syntax:
    $a = isset($b) ? $b : 42;
    $a = !empty($b) ? $b : 42;

New syntax:
    $a = $b ?? 42;
    $a = $b ?! 42;

### Example 2 : Direct assignment ###
Old syntax:
    $arr['key'] = isset($arr['key']) ? $arr['key'] : 42;
    $arr['key'] = !empty($arr['key']) ? $arr['key'] : 42;

New syntax:
    $arr['key'] ??= 42;
    $arr['key'] ?!= 42;

### Example 3 : Works with statements too ###
Old syntax:
    // a)
    $tmp = get_stuff('foo');
    $a = isset($tmp) ? $tmp : 42;

    // b)
    $tmp = get_stuff('foo');
    $a = !empty($tmp) ? $tmp : 42;

New syntax:
    // a)
    $a = get_stuff('foo') ?? 42;

    // b)
    $a = get_stuff('foo') ?! 42;

### Example 4 : Chaining ###
Old syntax [2]:
    $a = false;
    if (!empty($c) {
        $a = $c;
    } else {
        $tmp = get_stuff();
        $a = !empty($tmp) ? $tmp : false;
    }
    if ($a === false) {
        $a = !empty($c) ? $c : 42;
    }

New syntax:
    $a = $c ?! get_stuff() ?! $b ?! 42;

### Example 5 : Illegal syntax ###
    $a = $d ?? $c ?! $b ?? 42; // `??` and `?!` cannot be mixed.

## References ##
     * [1]: http://code.google.com/p/php-snow/wiki/EmptyIssetOperators
     * [2]: This could also be done by nesting ternary operators, but that gets
            even more unreadable I think.