On Mon, May 19, 2008 at 8:02 AM, Emil Dotchevski <emil@revergestudios.com> wrote:
Am Sonntag 18 Mai 2008 19:28:42 schrieb Giovanni Piero Deretta:
On Sun, May 18, 2008 at 3:52 PM, Maik Beckmann I'm not a guru, but Instead of a vector<shared_ptrs<T> >, I'have used a shared_ptr <vector<T> > to implement recursive data structures. A clone pointer would work even better.
Giovanni, very nice!
A standard conforming compiler is allowed to reject std::vector<T> for incomplete T.
Are you sure about it? I think that the standard says (I do not have it, I'm looking at the last draft): "In particular, the effects are undefined in the following cases: if an incomplete type is used as a template argument when instantiating a template component." I'm not a language lawyer, but does boost::shared_ptr<vector<T> > count as an instantiation? The definition of (implicit) template instantiation in the draft I have (14.7.1) says: "Unless a class template specialization has been explicitly instantiated (14.7.2) or explicitly specialized (14.7.3), the class template specialization is implicitly instantiated when the specialization is referenced in a context that requires a completely-deļ¬ned object type or when the completeness of the class type affects the semantics of the program. " In particular the example in this section shows that creating a pointer to a template specialization does not require an instantiation. Boost shared_ptr explicitly allows its parameter to be incomplete, so it will definitely not be used in a context that requires a completely defined object. The boost::shared_ptr constructor is another story of course. -- gpd