Assign array with __get

I think there is a lot  to say why is not working but just look at those
2 execution:

---------------- 1st
class A
{

       public function __get($name)
       {
               $this->$name = array();
               return $this->$name;
       }

       public function test()
       {
               $this->_zork;
               $this->_zork['bar'] = 67;
       }
}

$a = new A;
$a->test();

var_dump($a);
---------------- 2nd
class A
{

       public function __get($name)
       {
               $this->$name = array();
               return $this->$name;
       }

       public function test()
       {
               $this->_zork['bar'] = 67;
       }
}

$a = new A;
$a->test();

var_dump($a);

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.

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

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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:

  public function &__get($name);

I think is that the $this->anArray['bar'] = 4;

Generate the following bytcode:

0  FETCH_OBJ_W                                      $0      'anArray'
1  ZEND_ASSIGN_DIM                                          $0, 'bar'

Will the folloing :

echo $this->anArray;
$this->anArray['bar'];

0  FETCH_OBJ_R                                     $0      'anArray'
1  ECHO
...

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  to say why is not working but just look at those
2 execution:

---------------- 1st
class A
{

       public function __get($name)
       {
               $this->$name = array();
               return $this->$name;
       }

       public function test()
       {
               $this->_zork;
               $this->_zork['bar'] = 67;
       }
}

$a = new A;
$a->test();

var_dump($a);
---------------- 2nd
class A
{

       public function __get($name)
       {
               $this->$name = array();
               return $this->$name;
       }

       public function test()
       {
               $this->_zork['bar'] = 67;
       }
}

$a = 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'] = 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

Hi,

I came across a strange behavior when using the magic method __get and
some instance variable that should be an array.
Consider the following example:

class A
{

public function __get($name)
{
$this->$name = array();
return $this->$name;
}

public function test()
{
$this->_zork['bar'] = 67;
}
}

$a = 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

--

-- Mathieu Suen

--
Etienne Kneuss
http://www.colder.ch