Eric Niebler wrote:
Peter Dimov wrote:
Eric Niebler wrote:
Peter Dimov wrote:
Seeing so many variations of it is a pretty good indication that we need it in Boost. :-) So you're going to add it? :-)
I can't help but think that even if I did add the above, you wouldn't use it because of the virtual destructor,
You're right, because in xpressive alone I use counted_base in no less than 3 places where the virtual destructor would be needless overhead! Clearly, it can't be all that uncommon.
It may be common. The point is that we need to settle on a single version of boost::counted_base. The virtual destructor version does have its benefits: it's easier to understand and use (CRTP can be a bit hard to swallow) and it allows intrusive_ptr<counted_base> to be used as the intrusive version of shared_ptr<void> and void* (with the additional benefit of a working dynamic_cast.) counted_base is somewhat bicycle sheddish and I've considered adding one as documentation rather than code. But one problem with that is atomic_count being in detail. :-)
The following program exposes the problem for me with vc7.1, vc8 and gcc 3.4.4. If you comment out the friend functions and uncomment the global free functions, the problem goes away. I don't understand it -- is some name look-up subtlety at play here?
I don't understand it either. Comeau/EDG compiles it. A non-template counted_base doesn't have this problem, FWIW.