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Date: Mon, 13 Jun 2005 22:56:03 +0200
Reply-To: Sven Fuchs <svenfuchs@artweb-design.de>
Message-ID: <177634065.20050613225603@artweb-design.de>
To: "Ron Korving" <r.korving@xit.nl>
Cc: internals@lists.php.net
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Subject: Re[2]: [PHP-DEV] PHP 5.1
From: svenfuchs@artweb-design.de (Sven Fuchs)

Why isn't is possible in userland? Is there any problem with using
this? 

function ifsetor(&$var, $default = null) {
    return isset($var) ? $var : $default;
}

echo ifsetor($a, 'foo');
echo $a, $b;
echo ifsetor($a, 'foo');
echo isset($a) ? 'is set' : 'not set';

expected result:

foo
Notice: Undefined variable: a in [...]
Notice: Undefined variable: b in [...]
foo
not set

actual result:

foo
Notice: Undefined variable: b in [...]
foo
not set

php does not issue a notice on using $a after having called ifsetor()
once. But further calls to isset() and ifsetor() keep returning the
expected results.

I'd assume, the missing notice is rather a bug than a feature. So
ifsetor() is possible in userland.

--
Sven


> If it were possible at all to make a function accept unset variables without
> generating a notice, I think ifsetor() shouldn't even be implemented. People
> could then have the freedom to create such functions themselves. But
> unfortunately, it doesn't seem to be possible, unless you'd suppress every
> function call with a @, which I don't think is the way to go in this case.

> So if it would be possible somehow to create your own isset()-like functions
> in PHP-code, I'd say implement something that would make that possible, and
> ingore the whole ifsetor() discussion from that moment on. People would be
> free to write whatever function they'd prefer.

> Ron


> ""Sara Golemon"" <pollita@php.net> wrote in message
> news:38.CE.21296.BFD78A24@pb1.pair.com...
>> > > What about ifsetor for 5.1 ?
>> >
>> > Would anybody be interested in a parameter for ifsetor() that would
> treat
>> > isset() as !empty() or an alternative function that achieves this? I
> know
>> > I'd love to see that. I use empty() a lot more than isset().
>> >
>> In the interrest of KISS, I'd leave the emptiness concept out of the
>> picture.  Unlike isset-ness, an emptiness coalesce *can* be done in
>> userspace:
>>
>> function firstNotEmpty() {
>>     $vars = func_get_args();
>>     foreach($vars as $var)
>>         if (!empty($var)) return $var;
>>     return NULL;
>> }
>>
>> There's enough....contention over the undeniably useful and
>> not-implementable-in-userspace parts of this thread that it's not worth
>> muddling it up with things that are a simple matter to do in userspace.
> It
>> doesn't matter that notempty() and ifsetor() could easily be implemented
> by
>> the same opcode (just like isset/empty are).
>>
>> -Sara