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To: "'Derick Rethans'" <derick@php.net>,
	"'PHP Developers Mailing List'" <internals@lists.php.net>
Date: Mon, 3 Oct 2005 18:05:56 +0400
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Subject: RE: [PHP-DEV] $ref =& $this;
From: dmitry@zend.com ("Dmitry Stogov")
References: <Pine.LNX.4.62.0510031502130.13434@localhost>

Hi,

At first $ref =& $this; produced fatal error because of the bug (not by
design).
For example $ref->prop =& $this; worked and works without errors.

So my patch shouldn't be reverted in any case.

At second disallowing such assignments and passign $this by reference will
breake a lot of PHP4 code (Mamaba CMS).
In PHP4 passing $object by refernce and by value had completely different
semantic.

I don't see any reason to disallow 100% proper code (like the the
following).

class Child {
  function Child($parent) {
    $parent->children[] =& $this;
  }
}

Of course using "=& $this" user can breake $this value, but other languages
(C++) allows this too.
I don't think we should be paranoiacs.

Thanks. Dmitry.


> -----Original Message-----
> From: Derick Rethans [mailto:derick@php.net] 
> Sent: Monday, October 03, 2005 5:09 PM
> To: PHP Developers Mailing List
> Subject: [PHP-DEV] $ref =& $this;
> 
> 
> Hello,
> 
> Dmitry committed a fix earlier to ignore the & in the 
> statement above. I 
> think this is not a good thing to do as it's simply 
> conceptually wrong. 
> The first thing is that ignoring syntax without issuing a warning is 
> dubious because people might think it does actually work, and 
> secondly 
> because I think that the code above is wrong anyway - somewhat in the 
> same way that "$this = new foo();" is wrong.
> 
> There is never any need to assign $this by reference, nor to 
> pass it by 
> reference to a function as it's an object anyway, making the 
> references 
> pointless - I would even go as far as disallowing passing $this by 
> references to a function - where the reference has to be 
> ignored again, 
> otherwise it allows you to chantge $this to a different object with:
> 
> class Foo {
> 	function byRef(&$f) {
> 		$f = new Bar();
> 	}
> 
> 	function modifyThis() {
> 		$this->byRef($this);
> 	}
> }
> 
> I think we should prevent people from writing syntax like 
> this, as it is 
> not obvious what is going to happen. This means that we should revert 
> Dmitry's patch.
> 
> regards,
> Derick
> 
> -- 
> Derick Rethans
> http://derickrethans.nl | http://ez.no | http://xdebug.org
> 
> -- 
> PHP Internals - PHP Runtime Development Mailing List
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> 
>