[Boost-users] [Serialization] Serializing classes defined in DLLs

From: Topi Mäenpää (topi.maenpaa_at_[hidden])
Date: 2005-09-16 04:45:19

Hi,

How do I register classes that are defined in a dynamically loaded 
so/dll? Using BOOST_CLASS_EXPORT just causes "terminate called after 
throwing an instance of 'boost::archive::archive_exception'
   what():  unregistered void cast". My set-up is as follows:

class A {
public:
   A();
   virtual ~A() {}
private:
   // polymorphic archive stuff here
};

class B : public A {}

BOOST_CLASS_EXPORT(B);

Serializing instances of B through a A* works fine if B is defined in 
the main executable. Now, I have tried the following (approximately):

// An exported function that returns a void pointer
typedef void* (*func)();

int main()
{
   // Load a dynamic library
   dll lib = load_dll("mylib.dll");
   // Get a pointer to the instance creator function
   func instance_creator = (func)lib.resolve("instance_creator");
   // An instance of B is created in the dll and returned as a void*.
   A* a = (A*)instance_creator();

   ...
        
   archive & a; //throws unregistered void cast
}

B is both defined and exported in mylib.dll.

So, what is the deal? I don't understand the soul of BOOST_CLASS_EXPORT 
well enough to solve the problem myself. But since I'm using the dll 
version of the serialization library, I'd assume that the dynamically 
loaded dll (mylib.dll) and the main executable use the same address 
space for the archive classes. I would understand this if I encountered 
this problem with static linking because I'd need to inlude two copies 
of the serialization library...

Any advice?

Regards,
Topi