Robert Ramey wrote:
Are you sure this worked before? That would surprise me.
Absolutely. This worked for about half an year ;-)
The problem is that template that implement the "export" functionality are instantiated for each archive type previously "seen" in the header. So including the following
#include <boost/archive/text_oarchive.hpp> #include <boost/serialization/export.hpp>
BOOST_CLASS_EXPORT(C)
in multiple modules is going to produce multiple symbols at link time.
Yes, I see -- with the current implementation. Maybe, you changed the implementation recently?
My suggestion would be to include the archive headers only in the modules that actually invoke serialization. And that be only in one module. My intention was that each class header contain BOOST_CLASS_EXPORT for its classes and the the "main" or other module (see demo_pimpl) that actually invoked the serialiation would include the headers for the archive classes that are desired. This makes it easy to switch between archive types for things like debugging, etc.
This is fragile. If I have two modules, linked in one application, which both use serialization, then if they both include a single header with BOOST_CLASS_EXPORT, I'll get link error, right? I don't think it's realistic to expect that either: 1. Classes are serialized only in one module. 2. No header file is used by more that one module. In my case, I've moved BOOST_CLASS_EXPORT to an implementation file and it worked. I am not sure this solution is generally applicable -- one might want header-only class hierarchy... - Volodya