Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!news.mixmin.net!news2.arglkargh.de!news.n-ix.net!news.belwue.de!newsfeed.ision.net!newsfeed2.easynews.net!ision!newsfeed.arcor.de!newsspool3.arcor-online.net!news.arcor.de.POSTED!not-for-mail
Content-Type: text/plain; charset="ISO-8859-1"
Message-ID: <2977017.SPkdTlGXAF@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <php@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Mon, 18 Jul 2011 17:19:33 +0200
User-Agent: KNode/4.4.11
Content-Transfer-Encoding: 7Bit
Subject: Re: error message I don understand
Newsgroups: comp.lang.php
References: <4e2050e3$0$48996$dbd4f001@news.wanadoo.nl> <4e21e658$0$19265$a8266bb1@newsreader.readnews.com> <4e229b87$0$39844$dbd4d001@news.wanadoo.nl> <1661536.sHWYdyDnFx@PointedEars.de> <4e22f737$0$19237$a8266bb1@newsreader.readnews.com>
Followup-To: comp.lang.php
MIME-Version: 1.0
Lines: 44
NNTP-Posting-Date: 18 Jul 2011 17:19:33 CEST
NNTP-Posting-Host: 0aa48f99.newsspool2.arcor-online.net
X-Trace: DXC=mLa3;178l>Hk:C4l9A;OcOA9EHlD;3YcB4Fo<]lROoRA8kF<OcfhCOK9[GHo:1OE=IDZm8W4\YJNLUFDj8T]K0?CDmniOZG;K0KfW@^bdjG8JB
X-Complaints-To: usenet-abuse@arcor.de
Xref: x330-a1.tempe.blueboxinc.net comp.lang.php:2614

Denis McMahon wrote:

> Thomas 'PointedEars' Lahn wrote:
>> In the end an oversimplified, wrong explanation.  It is a syntactical
>> requirement, not a functional one:
>> 
>>   $a = x();
> 
> Here you're assigning the return value of the function x() to the
> variable $a.
> 
>>   $a[0] = 42;
> 
> Here you're writing to the variable $a (or rather, in this case, to an
> element of the array that is variable $a).
> 
> Neither of these is trying to assign (write) a value to the return value
> of the function call.

Yes, it is.  The return value of the function is a one-element array, and 
with that assignment I am writing to the same memory area (or another memory 
area that holds a copy of the former's content) by changing the first 
element of the array.  IOW, the return value is _not_ read-only.

> Whether you call the issue syntactical or not is just irrelevant and
> messing about with semantics.

You are mistaken.  The issue is a syntactical one, not a functional one, 
because a function call (currently) cannot occur on the left-hand side of an 
assignment expression in PHP, *regardless* of the return value of function 
to be called.

IOW, it does not make sense to say that "the return value is read-only" as 
the function is *never* *called* and *no* return value is obtained in the 
first place then.  This is a rather important difference because syntax 
errors are detected by the parser upon (JIT-)compilation already.


PointedEars
-- 
Anyone who slaps a 'this page is best viewed with Browser X' label on
a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
computer, another word processor, or another network. -- Tim Berners-Lee