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Date: Sun, 15 Jul 2012 12:50:11 -0300
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To: Amaury Bouchard <amaury@amaury.net>
Cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] RFC Proposal - Attributes read/write visibility
From: brandon.wamboldt@gmail.com (Brandon Wamboldt)

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This seems pretty useful, but could technically be accomplished using the
get/set syntax already proposed. Obviously this is a cleaner implementation
however.

On Sun, Jul 15, 2012 at 12:46 PM, Amaury Bouchard <amaury@amaury.net> wrote=
:

> Hi,
>
> Here is an RFC proposal about a syntax extension for PHP. The purpose is =
to
> manage precisely the visbiliy of attributes, by separating reading and
> writing access.
>
> First of all, I know there is already an RFC about attributes ("Property
> get/set syntax" [1]). Its goal is mainly different, but I'll discuss it
> lower.
>
>
> THE PROBLEM
> In my experience, one of the major usage of getters is when you want to
> have an attribute, readable (but not writable) from outside the object.
> More, the attribute's visibilty is then chosen between private and
> protected, depending on your inheritance design.
>
> The result is not really satisfying:
> 1. You have to write getter's code. Maybe, it's just a simple return, but
> every line of code should be useful, not a workaround.
> 2. You ended with 2 syntaxes; $obj->attr when the attribute is public, bu=
t
> $obj->getAttr() when you must use a getter. It's a bit schizophrenic.
>
>
> THE IDEA
> I suggest to be able to separate reading visibility and writing visibilit=
y,
> using a colon to separate them. If only one visibility is given, it will =
be
> used for both reading and writing access.
>
> For example:
> class A {
>     public $a;           // public reading, public writing
>     public:public $b;    // the same
>     public:protected $c; // public reading, protected writing
>     public:private $d;   // public reading, private writing
>     public:const $e;     // public reading, no writing allowed
>
>     protected $f;           // protected reading, protected writing
>     protected:protected $g; // the same
>     protected:private $h;   // protected reading, private writing
>     protected:const $i;     // protected reading, no writing allowed
>
>     private $j;         // private reading, private writing
>     private:private $k; // the same
>     private:const $l;   // private reading, no writing allowed
> }
>
> As you can see, I think that writing access should be more restrictive th=
an
> reading access (or equivalent to it). A "private:public" visibility would
> make no sense.
>
>
> SOURCE CODE
> I did a patch. It kinda works, but I'm still working on it (because I'm
> still learning Zend Engine's internals).
> The code on GitHub: https://github.com/Amaury/php-src
> All advises are welcome.
>
>
> PRIOR WORK
> As I said before, the "Property get/set syntax" RFC is in discussion. My
> proposal doesn't focus on the same goals, but they could be fully
> compatible.
>
> Thus, we would be able to write this kind of code:
> class A {
>     // $str has public reading and private writing,
>     // and manage french quotes
>     public:private $str {
>         get { return "=AB" . $this->str . "=BB"; }
>         set { $this->str =3D trim($value, "=AB=BB"); }
>     }
> }
>
> Maybe you saw that the "Property get/set syntax" RFC has an intended synt=
ax
> for read-only and write-only attributes. From my point of view, there is =
a
> deep and clean separation between a getter/setter syntax and an extended
> visibility syntax. It shouldn't be in the same RFC.
> More, the proposed "read-only" and "write-only" keywords are less precise
> and powerful than what I'm suggesting.
>
>
> I would be happy to discuss all that with you guys.
>
> Best regards,
>
> Amaury Bouchard
>
>
> [1] : https://wiki.php.net/rfc/propertygetsetsyntax-as-implemented
>



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*Brandon Wamboldt*
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