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Date: Tue, 18 Jun 2013 12:42:31 -0400
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To: Tjerk Anne Meesters <datibbaw@php.net>
Cc: Levi Morrison <morrison.levi@gmail.com>, PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] PR 287 - added use_keys argument to array_filter() [Discussion]
From: theanomaly.is@gmail.com (Sherif Ramadan)

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On Tue, Jun 18, 2013 at 11:37 AM, Tjerk Anne Meesters <datibbaw@php.net>wrote:

>
>
>
> The danger actually lurks in the cases whereby the second argument is
> accepted and with that (sometimes radically) change the semantics of the
> function; in fact, quite a few internal functions have this kind of
> switch-by-argument behaviour, such as "array_keys" to randomly name one.
>  And admittedly, this function when my PR goes through ;-)
>
>
>
That is a worse outcome, sure, but there is still danger in the former
scenario given that defaulting the callback to take two arguments causes
the wrong result:

var_dump(array_filter(['foo', '', 'bar'], 'strlen', true));

Warning: strlen() expects exactly 1 parameter, 2 given in - on line 1

Warning: strlen() expects exactly 1 parameter, 2 given in - on line 1

Warning: strlen() expects exactly 1 parameter, 2 given in - on line 1
array(0) {
}


Not only do we trigger the error handler (a large enough array causes a
performance issue), but we also get back an empty array as a result. That's
BC and performance loss that's simply unacceptable, so defaulting the
behavior to pass the key is simply out of the question.


>
> --
> --
> Tjerk
>

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