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/
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