On Mon, 2008-07-28 at 08:52 -0400, Frank Mori Hess wrote:
I don't think the zero-argument call to make_shared resolves to the variadic template, see the make_shared.hpp file.
I've seen that, but: a) I don't understand what the "new T()" vs. "new T" issue is - and there seems to be nothing in the code which explains that. It does use new T(), which should also work for new T( Args... ) if Args is a zero-sized parameter pack, shouldn't it? b) Looking at N2352 and N2691, there should be only one make_shared. Boost vs. GCC already shows that looking at a concrete implementation is not enough. Question is, what is/should be guaranteed by the standard. If nothing like this is guaranteed (probably because it's simply too late?), I would end up with non-portable code. Even then I would be interested in whether or not you, Peter, etc. think if something like that should be at least targeted for TR2... c) I just realized that the friend declaration is not yet correct. I think the correct (and generic) version should read: class A { // private ctors... A(); A( int, double ); // allow creation through make_shared template<typename T, typename... Args> friend std::shared_ptr<T> std::make_shared( Args&&... ); }; One might also need to add a friend declaration for allocate_shared if you intend to allow that, too. d) Besides the use case above, what do you think about using this pattern to allow shared_from_this to be called in the ctor? Is this possible? Would it be useful? Regards, Daniel