Re: destruction of cross-referenced objects

On Mon, December 4, 2006 7:21 pm, Arnold Daniels wrote: > I'm struggling with the problem that cross-referenced objects don't > get > destroyed. I can off course write a method to break the > cross-reference, > but that's kind of a pain in the butt, especially if the > cross-reference > is not strait forward. Seems to me that a simple unset() on the data members in userland coude so PHPs refcount is decremented ought to do it... If a user creates a monstrous data structure and doesn't prune it, how much responsibility can PHP take for that? But maybe I'm just being naive. > To solve this I'm thinking of building one of 2 thing: > 1.) Write a destroy() function which works much like a close function > on > a recourse, changing the object to a zval of type 'unknown'. > 2.) Specify that a property of an object does not count for the > reference count of a zval. I don't think this is a Good Idea... Seems like it would be WAY too easy for userland code to end up with a 0 for the refcount and then GC kicks in. > 3.) Write code to find cross-references and destroy the objects still. > > The first solution should be quite easy to implement, but you need to > call destroy() to free the object, introducing the whole alloc/free > responsibility thing to PHP. Just use unset() for this, rather than introduce yet another confusing function. > The second solution would require some extra keyword within the class, > but require no special code within the code using the object. Though I > wouldn't have a clue how how to implement this or what would be the > consequences. > I don't think the third solution is really possible or would at least > cause performance problems. Finding a "dead branch" of cyclic structures is basic CS stuff. Add a second temp "refcount" and start walking the graph. Either you end up with something known to be in the GLOBAL scope, or you don't. It can take a long time, depending on the size of the graph, but it's just pointer-chasing and integer arithmetic, so shouldn't be THAT slow. -- Some people have a "gift" link here. Know what I want? I want you to buy a CD from some starving artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So?