Hi David,
Trying to over design a program to avoid all shared ownership is what make C++ programming so unproductive and has all the negative consequences described in Section 1 in:
http://www.cs.sandia.gov/~rabartl/TeuchosMemoryManagementSAND.pdf
Designs with object sharing can be much less complex overall than designs with sharing. You just need decent tools to detect circular reference problems (and that is what the Teuchos::RCP class has).
Well, I fundamentally disagree with all of the above. Overuse of runtime polymorphism, thus dynamic allocation, and thus shared ownership (it's almost an inevitable progression) is one of the things that has made C++ programming unproductive, and those people I know who most zealously avoid it tend to be more productive than everyone else. IMO.
I couldn't agree more. C++ best practices has been evolving from dynamically-polymorphic designs to statically-polymorphic ones, but rather slowly, so I don't expect to see most competent programmers do the mental migration just yet. This requires a mindshift comparable to that of structured -> OO programming. I even wonder if this isn't a new paradigm altogether. For instance, it's been so long since I last wrote a virtual function that recently, I made the silly mistake of forgetting that, in a derived class, an overrided function doesn't have to specify the virtual keyword ;) Anyway. Speaking of value-semantics and moving (as opposed to sharing) objects... I recall a CUJ article in the mid 90's with a smart pointer offering a handle/body solution for value-semantics of dynamically allocated objects. I don't remember the details (such as using COW or what), nor the author, but I do remember that it was, IMO, simply brillant, but way ahead of its time. Compilers at the time could barely template two and two toghether, so the actual utility was rather impractical. I just thought that, maybe, C++0x finally got what it takes to tackle on something like that? IMO this would make for a terrific boost project, to the level of what shared_ptr used to be 15 years ago. Anyone? (I can't get into something like that without a time machine I'm afraid :) Best -- Fernando Cacciola SciSoft Consulting, Founder http://www.scisoft-consulting.com