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Date: Thu, 18 Mar 2010 12:49:03 +0100
Message-ID: <e666c3891003180449u7554c915y4732f9bd1b6583fb@mail.gmail.com>
To: "mathieu.suen" <mathieu.suen@easyflirt.com>
Cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] Assign array with __get
From: colder@php.net (Etienne Kneuss)

Hello,

On Thu, Mar 18, 2010 at 8:49 AM, mathieu.suen
<mathieu.suen@easyflirt.com> wrote:
> Etienne Kneuss wrote:
>>
>> Hello,
>>
>> On Wed, Mar 17, 2010 at 3:40 PM, mathieu.suen
>> <mathieu.suen@easyflirt.com> wrote:
>>
>>>
>>> Ionut G. Stan wrote:
>>>
>>>>
>>>> Hi,
>>>>
>>>> This is interesting and it appears the following change makes the
>>>> snippet
>>>> work as expected:
>>>>
>>>> =A0 public function &__get($name);
>>>>
>>>
>>> I think is that the $this->anArray['bar'] =3D 4;
>>>
>>> Generate the following bytcode:
>>>
>>> 0 =A0FETCH_OBJ_W =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0$0 =A0 =A0 =A0'anArray'
>>> 1 =A0ZEND_ASSIGN_DIM =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$0, 'bar'
>>>
>>> Will the folloing :
>>>
>>> echo $this->anArray;
>>> $this->anArray['bar'];
>>>
>>> 0 =A0FETCH_OBJ_R =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 $0 =A0 =A0 =A0'anArray'
>>> 1 =A0ECHO
>>> ...
>>>
>>>
>>>
>>> IMHO I think that the complexity of the VM is way to hight.
>>> That is something I am strongly agree with Gilad Bracha on adding new
>>> feature into a language:
>>>
>>
>> What exactly would you like it do? You've two options:
>>
>> 1) __get, define the property, and then __set?
>> 2) __get returns a ref that is modified
>>
>> The second option is taken by PHP.
>> In your case you return a value, not a reference.
>>
>
> I think there is a lot =A0to say why is not working but just look at thos=
e
> 2 execution:
>
> ---------------- 1st
> class A
> {
>
> =A0 =A0 =A0 =A0public function __get($name)
> =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->$name =3D array();
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return $this->$name;
> =A0 =A0 =A0 =A0}
>
> =A0 =A0 =A0 =A0public function test()
> =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->_zork;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->_zork['bar'] =3D 67;
> =A0 =A0 =A0 =A0}
> }
>
> $a =3D new A;
> $a->test();
>
> var_dump($a);
> ---------------- 2nd
> class A
> {
>
> =A0 =A0 =A0 =A0public function __get($name)
> =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->$name =3D array();
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return $this->$name;
> =A0 =A0 =A0 =A0}
>
> =A0 =A0 =A0 =A0public function test()
> =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->_zork['bar'] =3D 67;
> =A0 =A0 =A0 =A0}
> }
>
> $a =3D new A;
> $a->test();
>
> var_dump($a);
> ----------------
>

Nothing strange or unexpected here, in "1st" you define $this->_zork
in __get the first time you call it, meaning that you'll bypass the
__get for your next $this->_zork['foo'] =3D 2;

>
> Adding something that don't have side effect make the side effect
> work.... (more or less)
> You almost have to know how the VM is implemented in other to know what
> is going on.
> Nothing is obvious.
>
>>
>>>
>>> Look at the last paragraph:
>>> http://gbracha.blogspot.com/2009/09/systemic-overload.html
>>>
>>>
>>>>
>>>> On 3/17/10 3:55 PM, mathieu.suen wrote:
>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>>
>>>>> I came across a strange behavior when using the magic method __get an=
d
>>>>> some instance variable that should be an array.
>>>>> Consider the following example:
>>>>>
>>>>>
>>>>> class A
>>>>> {
>>>>>
>>>>> public function __get($name)
>>>>> {
>>>>> $this->$name =3D array();
>>>>> return $this->$name;
>>>>> }
>>>>>
>>>>> public function test()
>>>>> {
>>>>> $this->_zork['bar'] =3D 67;
>>>>> }
>>>>> }
>>>>>
>>>>> $a =3D new A;
>>>>> $a->test();
>>>>>
>>>>> var_dump($a);
>>>>>
>>>>>
>>>>> So could someone explain me what is the semantic of the above
>>>>> statements?
>>>>>
>>>>> Thanks
>>>>>
>>>>>
>>>>> -- Mathieu Suen
>>>>>
>>>
>>> --Mathieu Suen
>>>
>>>
>>> --
>>> PHP Internals - PHP Runtime Development Mailing List
>>> To unsubscribe, visit: http://www.php.net/unsub.php
>>>
>>>
>
> -- Mathieu Suen
>
>
>
>
>



--=20
Etienne Kneuss
http://www.colder.ch