On 22.09.2006, at 00:18, Robert Ramey wrote:
I also believe that things have been confused by an evolution in the original idea for save/load array. As I remember the motivation was that save/load array could be re-implemented differently for binary and/or mpi and/or other archives. Of course we have this now as the array_wrapper can be implemented differently for each archive. But now it seems that save/load array are going to be quite different for binary and mpi type archives. I think that at one point there might have been the idea that save/load implementations could be shared between different binary-type archives. But now it seems that binary_archive an mpi and/or other archives will have less in common than originally thought.
Our motivation was actually not that the save/load implementation code could be shared, but the dispatch code to decide for which types the optimized serialization can be used and for which it can't. That code is 50x bigger than the actual save_array/load_array implementations which are just ne or few-line dispatches to save_binary, MPI_Pack, or the creation of an MPI data type.
I think this evolution has led to code which is very hard for me to follow and which will be more work to maintain and support. I can't help but think that if 10x speed up of binary_archive were considered today, (given the wrapper and other changes), the enhancement would be less general and much simpler.
Sure, if you want to restrict the enhancements to binary archives and primitive data types a slightly simpler implementation is possible. That solution would not be scalable, however. Matthias