Re: Property Accessors 1.2 for Final Review before Vote

On 1/2/13 4:18 PM, Clint Priest wrote:

Omitting isset/unset has the same effect as declaring it without a body. This is described in the RFC under Automatic Implementations with this line: Note that isset/unset implementations will always be provided if they are not defined or if they are explicitly auto-defined (as above).

I think the RFC could make this clearer: "isset & unset are always provided with the default implementations unless the author provides his/her own." Looking closer at the default implementations of isset/unset, I'm worried these could lead to confusion. Consider this code: class TimePeriod {

    private $Seconds = 3600;
    public $Hours {
        get { return $this->Seconds / 3600; }
        set { $this->Seconds = $value; }
    }

} The RFC's default implementation is always bound to the shadow property, so here's what you really get: class TimePeriod {

    private $Seconds = 3600;
    public $Hours {
        get { return $this->Seconds / 3600; }
        set { $this->Seconds = $value; }

        // auto-generated
        isset { return $this->Hours != NULL; }
        unset { $this->Hours = NULL; }
    }

} Note the resulting behavior: $t = new TimePeriod; $t->Hours; // 1 isset($t->Hours); // false !? unset($t->Hours); $t->Hours; // still 1 Effectively, authors who don't base their getters/setters on the shadowed property must be urged to create their own isset/unset because the default ones would be useless. I'm not crazy about this. I'd prefer these default implementations: isset { return $this->__getHours() != NULL; } unset { $this->__setHours(NULL); } $t = new TimePeriod; $t->Hours; // 1 isset($t->Hours); // true unset($t->Hours); $t->Hours; // null isset($t->Hours); // false Note these also work as expected when using the default get/set implementations. Of, course, my implementations don't actually *work* because you can't call an accessor from an accessor... Steve Clay -- http://www.mrclay.org/