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Date: Tue, 24 Feb 2015 17:55:16 +0400
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To: Nikita Popov <nikita.ppv@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Re: Mark some functions with PREFER_REF
From: dmitry@zend.com (Dmitry Stogov)

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On Tue, Feb 24, 2015 at 2:37 PM, Nikita Popov <nikita.ppv@gmail.com> wrote:

> On Mon, Feb 23, 2015 at 10:36 PM, Nikita Popov <nikita.ppv@gmail.com>
> wrote:
>
> > Hi internals!
> >
> > With regard to my E_STRICT RFC [1] Yasuo and another off-the-record mail
> > expressed a concern about the "Only variables should be passed by
> > reference" strict standards warning.
> >
> > This notices makes sense in a lot of places, e.g.
> >
> >     array_push(getArray(), 1, 2, 3);
> >
> > is totally pointless code if getArray() doesn't return a reference.
> > array_push will just modify a temporary array in this case.
> >
> > However other usages like
> >
> >     $top = array_pop(getArray());
> >
> > are less clear: array_pop() both has a side-effect (removing the top
> > element of an array) and a meaningful return value (the top element of
> the
> > array). As PHP does not have a dedicated function for getting the
> > first/last element of an array, many people use code like this (which
> > currently throws E_STRICT) instead.
> >
> > I'd like to mark a few such functions with PREFER_REF (i.e. allow passing
> > both references and values). In particular array_pop() and array_shift().
> >
> > Does anybody have a problem with us doing this? Are there other functions
> > which should use PREFER_REF?
> >
> > The motivation behind this is to make sure we only throw this notice in
> > cases where the code is actually buggy/nonsensical instead of just making
> > people ignore it altogether.
> >
>
> A few people have pointed out OTR that the same applies to reset() and
> end(). Both can be used to get the first/last element (and change the IAP
> as a side effect). So I'd add PREFER_REF to those as well. (Interestingly
> key() and current() already use PREFR_REF even though they don't modify the
> array at all, probably this is a performance optimization.)
>

key() and current() shouldn't use it.
It was an optimization from PHP5 time that makes for PHP-7 more harm than
benefit.

According to array_pop(), array_shift(), reset() and end(), it's not a
problem to avoid this warning.
But note that such usage of these functions may be really inefficient,
because they may need to duplicate the passed array first.

Thanks. Dmitry.



>
> Nikita
>

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