[boost] Serialization library question

From: Matthias Troyer (troyer_at_[hidden])
Date: 2002-09-27 11:03:52

Hi Robert,

I have looked at the serialization library in even more detail but 
there is still the issue with large data sets that I do not fully 
understand. I often have large vectors of small classes,

i) To construct a simple example:

struct Item {
  int x;
  int y;
};

std::vector<Item> v(10000000);

If I now serialize v, it seems that there will be an overhead unless I 
write a specialized save function for std::vector<Item>. Is that 
corrrect? That would be very inconvenient,
as I have lots of such small classes with just a few bytes of contents 
bbut many member functions.

ii) I do not always want to serialize a std::vector of a POD by calling 
operator<< for each element. Consider for example a

std::vector<int> v(10000000)

I need to serialize this into three different types of archives

a) a message buffer for use with MPI. Here I want to do something like

memcpy(buffer,&v[0],v.size()*sizeof(int))

b) a file or buffer in XDR format. Here I want to use just one call to 
xdr_vector instead of millions of separate calls to xdr_int

c) output to a text file. here the standard way of writing each number 
is just perfect

Thus, I need runtime polymorphism for the serialization of a 
std::vector, which I do not seem to have in your current library. You 
have operator<< as virtual functions for the POD types. I additionally 
need similar virtual functions for writing C-arrays of POD types - 
which your library currently lacks. Would it be possible to add such 
functions?

All the best,

Matthias