On Fri, Oct 17, 2008 at 12:42 PM, troy d. straszheim <troy@resophonic.com> wrote:
Ling Li wrote:
Thanks! Using streambuffer or std::istringstream/std::ostringstream is indeed very convenient.
Has anyone thought about introducing default values in serialization to save the storage size (or the number of bits tranferred over network)? I hacked NVP and make_nvp to support this as an optional feature, and it works fine for me. If that sounds something might be useful to others, I can paste the patch here.
You can get these numbers by making a filter device that counts bytes, (iirc there is an example in iostreams) or by serializing to, say, a vector<char> via via one of the iostreams push_back devices and getting the container's size after the archive is closed. Serializing to a vector is also convenient if you want to, say, use boost::crc to take and transmit checksums with the data.
-t
Sorry that I didn't make myself clear. I meant to reduce the archive size (not count the size). For example, in demo_gps.hpp, instead of ar & boost::serialization::make_nvp("hour", hour) one might want to use ar & boost::serialization::make_nvp("hour", hour, 11) so that if the hour is 11, it is not serialized in the archive. During deserialization, if the hour is missing in the archive, 11 will be the default value. I have to say this can only be applied to archives with names, e.g., XML. And one can't use default values for elements in a vector unless we give each element a name (e.g., the index). So compared to using the binary archive, it might not be a save in archive size.