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

From: Ivan Rachev (ivanr_at_[hidden])
Date: 2005-07-10 09:36:23

Yes, after further understanding of how boost::serialization works I 
came to the conclusion that the sample works.

Thanks,
Ivan

Robert Ramey wrote:
> I believe your example should work as written. Where does it fail?
> 
> Robert Ramey
> 
> Ivan Rachev wrote:
> 
>>Does anyone have an idea how to serialize dynamic arrays of objects?
>>
>>An example follows at the end. Its weakness shows up when an outside
>>pointer points to an element in the array. The problem is that the
>>type being serialized is T but not T*.
>>
>>Thanks,
>>Ivan
>>
>>
>>
>>
>>#include <fstream>
>>
>>#include <boost/archive/text_iarchive.hpp>
>>#include <boost/serialization/access.hpp>
>>#include <boost/serialization/split_member.hpp>
>>
>>class A
>>{ friend class boost::serialization::access;
>>   template<class Archive>
>>   void serialize(Archive & ar, const unsigned int version) {}
>>};
>>
>>//IVAN Element always points to the beginning of an array of
>>//     'Size' elements. The array is NOT null-terminated. If
>>//     size == 0, Elements may hold an undefined value. User
>>//     is responsible for initializing, new-ing and delete-ing.
>>//     Assumption: if there is an outside pointer to an object
>>//                 inside this array, after loading the array
>>//                 that pointer will hold a different object.
>>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;
>>     //TODO: 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()
>>{
>>   DynamicArray<A> ArrayOfAs;
>>   A* secondElement;
>>
>>   std::ifstream ifs("test.txt");
>>   boost::archive::text_iarchive ia(ifs);
>>   ia & ArrayOfAs;
>>   ia & secondElement; // this guy will point to a copy of the
>>                       // 2nd element but NOT the 2nd element itself
>>
>>   delete [] ArrayOfAs.Element;
>>}