On Wed, Nov 19, 2008 at 2:37 PM, J.D. Herron <jotadehace@gmail.com> wrote:
If I have a dynamically loaded factory interface that returns a shared_ptr, the factory implementation causes the templates to generate the virtual function code within the factory library. Everything is fine as long as the library stays loaded but if the library is unloaded, any client code holding the shared pointer to an object generated by that factory now has an invalid virtual function table for the sp_counted_base it holds. So when the reference count goes to zero an access violation is generated.
One solution is to "inject" the shared_ptr that would crash if a DLL is unloaded with another shared_ptr that keeps the DLL afloat. I've also done this with the boost::function objects that are passed to the client to be used as factories. Another strategy which doesn't necessarily work in the case of shared_ptr but works for other things (like std::type_infos obtained from a DLL) is to use weak_ptr to detect that the DLL is gone and accessing the object will crash the program, and throw an exception instead. Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode