On Feb 25, 6:41 pm, "Alf P. Steinbach" <al...@start.no> wrote: > * Chris Gray: > > > Lawrence D'Oliveiro <l...@geek-central.gen.new_zealand> writes: > > >> In message <op.u8nfpex8y5e...@laptopwanja>, Wanja Gayk wrote: > > >>> Reference counting is about the worst technique for garbage collection. > >> It avoids the need for garbage collection. It means I can write things like > > > I'm by no means an expert, but how does reference counting deal with > > arbitrary long cycles of references (btw I've *written* a simple > > reference counter for a programming language)? > > Generally it doesn't. Some solutions have however been proposed for > std::shared_ptr in C++. None have made it to any noteworthy status, but they > demonstrate that there are more or less practical solutions for the most > common > cases. > > Currently the upshot is that if you need the kind of self-referential > spaghetti > structure (no offense) created by mathematical expressions that refer to each > other, then you've passed beyond what can be handled practically by reference > counting alone or even in combination with cycle handling techniques. > > For that you're better off with some functional language, or Python... ;-) > > > When I asked someone whose knowlege of Java I trust, he said that modern > > Java's do both reference counting and garbage collection. That was 2 or 3 > > years ago. I would have guessed that Python was the same. > > Yes, Python adds general garbage collection to deal with cycles. > > Essentially the reference counting deals efficiently and immediately with > objects created by expression evaluation, while the general garbage collection > deals with cyclic structures. > > But there's no magic: in particular in Java, Python and like languages you > must > still remember to remove references installed in singletons and globals (e.g. > for event notifications), otherwise objects will still be referenced and thus > not garbage collected, causing a memory leak.
Is that really considered a leak, a single instance of an uncollected global as opposed to a function that is called millions of times, and each time it's called creates uncollected temporary variables? > > Cheers & hth., > > - Alf -- http://mail.python.org/mailman/listinfo/python-list
