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Date: Thu, 23 Jun 2011 17:09:06 +0200
Message-ID: <BANLkTikZnu=4HzrrojWs1atq_RYJZRBmYQ@mail.gmail.com>
To: Stefan Neufeind <neufeind@php.net>
Cc: internals@lists.php.net
Content-Type: multipart/alternative; boundary=000e0cd733f862015a04a66277cd
Subject: Re: [PHP-DEV] Variable scopes for language constructs (foreach, ...)
From: tyra3l@gmail.com (Ferenc Kovacs)

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On Thu, Jun 23, 2011 at 5:03 PM, Stefan Neufeind <neufeind@php.net> wrote:

> Hi,
>
> I've lately discussed with a colleague which scopes of variables exist
> for PHP or would probably make sense. In general I think the general
> idea of having variables available all throughout a function is okay as
> this allows things like
>
> foreach($vals as $v) {
>  // ...
>  $found = true;
> }
> if($found) {
>  // ...
> }
>
> (setting $found inside the loop while still being able to access it
> outside)
>
> But the interesting part is that $v is also still available outside the
> loop (last value). While most people would say this is not a big
> problem, it can become problematic when using references.
>
> foreach($vals as &$temp) {
>  // ...
> }
> // ...
> $temp = 5;
> (when you don't think about the reference anymore but want some
> temp-variable)
>
>
> If this has been "throughly discussed" before, please excuse. But if not
> maybe somebody could share his oppinion on the following proposal.
>
> What if we (for example with PHP 5.4 or if not possible maybe with the
> next one) change the behaviour so that
>
> * variables used for key/value in foreach (probably other places?) would
> be limited to that loop-scope
>
> and maybe
> * variable $found in the first example would need to be initialised
> before the loop. Otherwise it would be a new variable inside the scope
> of foreach that would be gone afterwards
>
> and/or maybe
> * allowing to explicitly limit variable-scopes inside blocks, for
> example by allowing    var $found   somewhere inside a function to allow
> things like
>
> if($a) {
>  var $temp;
>
>  $temp = 5;
> }
> // and $temp would be gone here; was limited to the scope in which it
> was defined by var
>
>
> Hope this is not too much of a non-sense idea to you :-)
>
>
Hi,

it was discussed many times on the list, and this behavior is also
documented, see
http://php.net/manual/en/control-structures.foreach.php

"Reference of a $value and the last array element remain even after the
foreach loop. It is recommended to destroy it by unset()."

personally I find that weird, and unintuitive, but changin that in a major
or minor version could be changed if we chose to.

Tyrael

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