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Date: Tue, 9 Oct 2012 15:01:05 +0200
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To: Clint Priest <cpriest@zerocue.com>
Cc: "internals@lists.php.net" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Propety Accessors v1.1
From: nikita.ppv@gmail.com (Nikita Popov)

On Mon, Oct 8, 2012 at 1:52 PM, Clint Priest <cpriest@zerocue.com> wrote:
> It's been a while since I posted any updates about this, a few individuals have been asking about it privately and wanting me to get it out the door for PHP 5.5 release.  It's come a long way since the last time I posted about it.
>
> RFC Document: https://wiki.php.net/rfc/propertygetsetsyntax-as-implemented
>
> Example Usage:
>
> class TimePeriod {
>     private $Seconds = 3600;
>
>     public $Hours {
>         get { return $this->Seconds / 3600; }
>         set { $this->Seconds = $value; }
>         isset<http://www.php.net/isset> { return isset<http://www.php.net/isset>($this->Seconds); }
>         unset<http://www.php.net/unset> { unset<http://www.php.net/unset>($this->Seconds); }
>     }
> }
>
> Changes / Updates
>
> *         isset/unset accessor functions now implemented (object & static context, auto implementations, etc)
>
> *         static accessor now fully functional
>
> *         Reference functionality validated, tests written
>
> *         All operators have been tested, tests written
>
> *         read-only and write-only keywords: Added explanation of reasons for inclusion at the top of the appropriate RFC section
>
> *         Tested for speed, approaches or meets __get() speed.
>
> Internally things have changed quite a bit
>
> *         cleaned up and simplified
>
> *         had been using 4 to 5 additional fn_flag slots, now down to two (READ_ONLY and WRITE_ONLY)
>
> *         the automatic implementations now compiled internal php code, this greatly simplified that part of the code and future proofed it.
>
> The code is available at the url below and is up to date with master, all tests pass.
> https://github.com/cpriest/php-src
>
> I'd like to get this project wrapped up in time to make it to the 5.5 release, only a few things remain to be completed/updated:
>
> *         Check on reflection code written prior to major changes (tests still pass)
>
> *         Add a few more reflection functions that were requested
>
> In total there are 79 tests for this new functionality, if there are any others that I have missed, please let me know.

What concerns me with the current implementation is that it leaks many
implementation details, in particular the fact that the accessors are
implemented as *real* __getXYZ methods and automatic implementations
also use *real* $__XYZ properties.

A few examples:

## 1 - __getProperty() method directly callable

class Test {
    public $property {
        get { return 123; }
    }
}

$test = new Test;
var_dump($test->property); // int(123)
var_dump($test->__getProperty()); // int(123)

## 2 - __getProperty() method exposed via exception

class Test {
    public $throwingProperty {
        get { throw new Exception; }
    }
}

(new Test)->throwingProperty;

exception 'Exception' in /home/nikic/dev/php-src/t29.php:9
Stack trace:
#0 /home/nikic/dev/php-src/t29.php(31): Test->__getthrowingProperty()
#1 {main}

## 3 - Can directly access $__automaticProperty and even unset it
(causing notices in the internal code)

class Test {
    public $automaticProperty {
        get; set;
    }

    public function getAutomaticProperty() {
        return $this->__automaticProperty;
    }

    public function unsetAutomaticProperty() {
        unset($this->__automaticProperty);
    }
}

$test->automaticProperty = 'foo';
var_dump($test->getAutomaticProperty());
$test->unsetAutomaticProperty();
var_dump($test->automaticProperty);

string(3) "foo"

Notice: Undefined property: Test::$__automaticProperty in
/home/nikic/dev/php-src/t29.php on line 13
NULL

=====

I feel like this approach to the implementation will be a big can of
worms. Sure, it works, but it is rather fragile and the enduser ends
up dealing with internal stuff which he ought not care about. I think
it would be better to cleanly separate out the accessor
implementation. It might require more code now, but will be better in
the long run.

Nikita