Re: [Boost-users] Serialization of dynamic data

From: Anders Sundman (anders.sundman_at_[hidden])
Date: 2007-02-01 14:54:37

Ok, my bad. I've found the docs:

http://www.boost.org/libs/serialization/doc/serialization.html#splitting

But the general question remains, what to do with dynamic data?

It's often the case that I find a T* and a size in classes. I've been 
thinking about introducing some kind of convenience functions for this. 
Perhaps something along these lines:

template<class T, class Archive>
void saveBuf(Archive & ar, const T * buf, size_t size) {
        bool isNull = (buf == 0);
        ar << size;
        ar << isNull;
        if (!isNull)
                ar.save_binary(buf, size * sizeof(T));		
}

template<class T, class Archive>
void loadBuf(Archive & ar, T *& buf, size_t & size) {
        bool isNull;
        ar >> size;
        ar >> isNull;

        if (buf != 0) {
                delete buf;
                buf = 0;
        }

        if(!isNull) {
                buf = new T[size];		
                ar.load_binary(buf, size * sizeof(T));
        }
        else {
                buf = 0;
        }
}

What do you thing about that? Any obvious problems? Are there perhaps 
already something like this in the library?

// Anders Sundman

Anders Sundman skrev:
> Hi!
> 
> About the boost::serialization library, what is the best way to handle 
> dynamic data in classes? Any idéas, suggestions or caveats? I didn't 
> manage to find anything about this in the docs.
> 
> Consider the following sample class:
> 
> struct Dyn {
> 	Dyn(int s) : data(0), size(s) {
> 		data = new char[size];
> 	}
> 
> 	~Dyn() { delete data; }
> 
> 	char* data;
> 	int size;
> 
> private:
> 	friend class boost::serialization::access;
> 	template< class Archive > void serialize( Archive &ar, unsigned int ver ) {
> 		// -> ar & data; What to do here?
> 		ar & size;
> 	}
> };
> 
> What to do with the data pointer?
> 
> Is there any way to determine (in the serialize function) if a 
> serialization or "de-serialization" is taking place? And have different 
> behaviours - either allocating a new char[x] or copying data to the archive?
> 
> Is there any way to store dynamic data in an archive?
> 
> Best regards,
> Anders Sundman