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Date: Thu, 18 Mar 2010 10:24:35 +0100
Message-ID: <660eb66f1003180224g5662ba1dtb123c3ee88a3a3e5@mail.gmail.com>
To: "mathieu.suen" <mathieu.suen@easyflirt.com>
Cc: Etienne Kneuss <webmaster@colder.ch>, internals@lists.php.net
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Subject: Re: [PHP-DEV] Assign array with __get
From: peter.e.lind@gmail.com (Peter Lind)

> I think there is a lot =C2=A0to say why is not working but just look at t=
hose
> 2 execution:
>
> ---------------- 1st
> class A
> {
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0public function __get($name)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0{
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0$this->$name =3D a=
rray();
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return $this->$nam=
e;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0}
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0public function test()
> =C2=A0 =C2=A0 =C2=A0 =C2=A0{
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0$this->_zork;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0$this->_zork['bar'=
] =3D 67;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0}
> }
>
> $a =3D new A;
> $a->test();
>
> var_dump($a);
> ---------------- 2nd
> class A
> {
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0public function __get($name)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0{
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0$this->$name =3D a=
rray();
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return $this->$nam=
e;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0}
>
> =C2=A0 =C2=A0 =C2=A0 =C2=A0public function test()
> =C2=A0 =C2=A0 =C2=A0 =C2=A0{
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0$this->_zork['bar'=
] =3D 67;
> =C2=A0 =C2=A0 =C2=A0 =C2=A0}
> }
>
> $a =3D 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 $this->zork['blah'] =3D 'blah'; no longer indirectly
calls __get as object::$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

--=20
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