Ian McCulloch wrote:
Peter Dimov wrote:
template<class Archive, class It> inline void save_sequence(Archive & ar, It it, unsigned count) { while(count-- > 0){ //if(0 == (ar.get_flags() & boost::archive::no_object_creation)) // note borland emits a no-op without the explicit namespace boost::serialization::save_construct_data_adl(ar, &(*it), 0U); ar << boost::serialization::make_nvp("item", *it++); } }
template<class Archive, class Container> inline void save_collection(Archive & ar, const Container &s) { // record number of elements unsigned int count = s.size(); ar << make_nvp("count", const_cast<const unsigned int &>(count)); save_sequence( ar, s.begin(), count ); }
unless I'm missing something fundamental.
So what's all the fuss about?
That isn't quite all that needs to be done.
You are right, a std::vector needs to be special-cased to use a pointer.
(1) minor nit: an interface that uses (iterator, size) would be better than a container-based algorithm because that would make it easier to do optimizations based on the iterator type (eg, memcpy, or MPI operations in the case of a pointer, or maybe some kind of distributed iterator in combination with a parallel IO library?).
I don't understand.
template<class Archive, class It> inline void save_sequence(Archive & ar, It it, unsigned count)
looks decidedly (iterator, size) based to me.
Also, the collection isn't necessarily in the form of a container (although a proxy container would probably suffice for that case, and come to think of it, to handle resizing the container on load it might actually be preferable).
I don't understand this either.
(2) another minor nit: it is probably more convenient to handle the details of save_sequence() inside the archive (similarly to other primitive types), rather than as a free function.
The point is that you can overload the free function inside your archive's namespace.
(3) : save_collection() [or some functional equivalent] isn't part of the public interface of the serialization library. For whatever reason this seems to be the sticking point.
save_collection isn't - and probably shouldn't - but save_sequence would be.