Hi all,
Since around alpha1, I've been doing some experimenting with closures,
most recently in the form of a filter chain implementation, and I've
discovered that as of beta1 (as was noted in the "removal-of-$this"
RFC) that there is no way to access private or protected members of
any class inside a closure, regardless of where it is defined.
I realize that the question of implicit $this support for closures has
already been discussed and decided upon temporarily (and I certainly
have no wish to rehash it again), however, it seems logical that even
without being bound to an object, closures should still inherit the
scope in which they're defined. Otherwise, this creates a confusing
inconsistency within the language. Consider the following:
class Exposed {
private $_property;
public function __construct($data = null) {
$this->_property = $data;
}
public function getProtected($self, $property) {
return $self->$property;
}
}
$object1 = new Exposed('secret');
$object2 = new Exposed();
// successfully echos "secret"
echo $object2->getProtected($object1, '_property'));
Because of PHP's scope and visibility rules, this works even though
$object1 and $object2 are only associated by common parentage. While
this may have no technical significance, since a closure is actually
it's own class, in practical terms it puts a damper on the usefulness
of the implementation, and is a bit of a "WTF", particularly when
considered in context with "use", which allows closures to inherit and
even modify variables in the declaring scope, regardless of where they
are called.
Again, to clarify, I am not arguing for $this support to be added back
to closures (though if a consensus could be reached before 5.3 final,
that'd be great, too :-)). I am simply suggesting that the current
implementation might be improved and made more consistent (without
designing it into a corner concerning future decisions) by allowing a
closure defined in class X to follow the same rules as any other
method also defined in X.
Any thoughts or feedback would be very much appreciated. :-)
Thanks for your time and consideration,
- Nate Abele
Lead Developer, CakePHP
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