Re: [Boost-users] [serialization] serializing dynamic arrays ofintegral types

From: Robert Ramey (ramey_at_[hidden])
Date: 2005-07-10 15:29:00

Addresses of primitive types are generally not tracked by default.  So
replacing A with a char would not give a desired result. This is described
in the manual under the section of seriailzation traites/tracking and
serialization of pointers.

A solution would be to make a "trackable char" using STRONG_TYPE or some
other sort of wrapper to distinguish a char from a your own chartype.

Note that if you make a few small changes in your program - and are using
current CVS version (1.33 - real soon now) you will an error message to
alert you to this problem.  Here is my updated version of your program.

Ivan Rachev wrote:
> Hi Martin,
>
> If class A from the example is replaced by char, how should this
> situation be handled? Code follows at the end.
>
> Thanks,
> Ivan
>
>
>
>
> template <typename T>
> struct DynamicArray
> {
>      int Size;
>      T* Element;
>
>      friend class boost::serialization::access;
>      template<class Archive>
>      void save(Archive & ar, const unsigned int version) const
>      {
>        ar & Size;
>        for (int i = 0; i < Size; ++i)
>          ar & Element[i];
>      }
>      template<class Archive>
>      void load(Archive & ar, const unsigned int version)
>      {
>        ar & Size;
>        assert(Size >=0);
>        if (Size > 0)
>          {
>          Element = new T[Size];
>          for (int i = 0; i < Size; ++i)
>            ar & Element[i];
>          }
>      }
>      BOOST_SERIALIZATION_SPLIT_MEMBER()
> };
>
> int main(int argc, char* argv[])
> {
>      DynamicArray<char> ArrayOfAs, ArrayOfAs2;
>      ArrayOfAs.Element = new char[5];
>      ArrayOfAs.Size = 5;
>      char* secondElement = &ArrayOfAs.Element[1];
>      char* secondElement2;
>
>      std::stringstream stream;
>      {
>       boost::archive::text_oarchive oa(stream);
>       oa & ArrayOfAs;
>       oa & secondElement;
>
>      }
>
>      {
>      boost::archive::text_iarchive ia(stream);
>      ia & ArrayOfAs2;
>      ia & secondElement2;
>
>      }
>
>      assert(secondElement2 == &ArrayOfAs2.Element[1]);
>
>     delete [] ArrayOfAs.Element;
>     delete [] ArrayOfAs2.Element;
> }