Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:47431
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain easyflirt.com designates 91.199.255.56 as permitted sender)
Message-ID: <4BA3A147.2020506@easyflirt.com>
Date: Fri, 19 Mar 2010 17:07:35 +0100
User-Agent: Thunderbird 2.0.0.24 (X11/20100317)
MIME-Version: 1.0
To: "Ionut G. Stan" <ionut.g.stan@gmail.com>
CC: internals@lists.php.net
References: <4BA0DF61.1010907@easyflirt.com> <4BA0E39C.7020600@gmail.com>	 <4BA0E9E8.8000404@easyflirt.com>	 <e666c3891003171419t35b0df06v6c1d502c270154de@mail.gmail.com>	 <4BA1DB19.1080608@easyflirt.com>	 <660eb66f1003180224g5662ba1dtb123c3ee88a3a3e5@mail.gmail.com>	 <4BA25919.8090805@easyflirt.com> <e666c3891003181956j7c64948cq5ca791be21ab1dbc@mail.gmail.com> <4BA37E11.9080403@gmail.com>
In-Reply-To: <4BA37E11.9080403@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] Assign array with __get
From: mathieu.suen@easyflirt.com ("mathieu.suen")

Right I could work around the issue with the return by reference without 
any problem.
I am still thinking that if you try to write a meta-circular interpreter 
you gonna work very hard
to make this subtleties worked. And according to "Shriram Krishnamurthi" 
in his textbook PLAI:

" a truly powerful language is one that makes it easy to write its 
meta-circular interpreter."

-- Mathieu Suen



Ionut G. Stan wrote:
> I guess what Mathieu is trying to say is that this:
>
>     class Foo
>     {
>         public $bar = array();
>     }
>
>     $foo = new Foo;
>     $foo->bar[3] = 1;
>
>     var_dump($foo);
>
>
>
>
> ...is inconsistent with this:
>
>     class Foo
>     {
>         public function __get($property)
>         {
>             if (! isset($this->$property)) {
>                 $this->$property = array();
>             }
>
>             return $this->$property;
>         }
>     }
>
>     $foo = new Foo;
>     $foo->bar[3] = 1;
>
>     var_dump($foo);
>
>
>
>
> ...or even this:
>
>     class Foo
>     {
>         private $bar = array();
>
>         public function __get($property)
>         {
>             return $this->$property;
>         }
>     }
>
>     $foo = new Foo;
>     $foo->bar[3] = 1;
>
>     var_dump($foo);
>
>
> Now, I'm not really sure this is that bad, as there may be use cases 
> where one would like to return different values every time __get is 
> called. And, as I wrote in a previous email, there are ways to work 
> around this inconsistency by using return by reference, so everybody 
> can be happy. I think.
>
>
>
> On 3/19/10 4:56 AM, Etienne Kneuss wrote:
>> On Thu, Mar 18, 2010 at 5:47 PM, mathieu.suen
>> <mathieu.suen@easyflirt.com>  wrote:
>>> Peter Lind wrote:
>>>>
>>>> On the contrary, it's quite obvious what's going on. In both examples
>>>> __get() returns an array as PHP would normally do it (i.e. NOT by
>>>> reference) which means that if you try to modify that you'll end up
>>>> modifying nothing much. However, in your second example, the point at
>>>> which you call __get() indirectly comes before the assign to the zork
>>>> array - hence, the $this->zork['blah'] = 'blah'; no longer indirectly
>>>> calls __get as object::$zork now exists.
>>>>
>>>>   In other words, this is down to you confusing passing a variable by
>>>> reference and passing it by value: PHP normally passes arrays by
>>>> value, so when __get() returns an array, you're working on a copy of
>>>> the array you returned. As someone noted earlier, you can easily
>>>> change the behaviour of __get to return variables by reference, should
>>>> you want to. However, I personally wouldn't want this to be default
>>>> behaviour as that would make debugging apps much more annoying -
>>>> things should be consistent, even if consistency at times confuse
>>>> people.
>>>>
>>>> Regards
>>>> Peter
>>>>
>>>>
>>
>>