basically you have to a) "register" or "export" any concrete classes serialized. b) serialize the base object from every derived class - including intermedieate ones. c) If you use export - it shoiuld be after the *_archive.hpp files. If its not - it should fail to compile That's all that should be necessary. It has been my intention to permit "export" to be only in the header. I don't think that 1.32 it quite worked out that way but I'm trying to fix this. Robert Ramey Eric wrote:
Hi Robert (and Jeff):
Actually, the export.hpp has to come after any *archive.hpp due to the "trick" used to instantiate the appropriate code.
That was the problem! I only used the xml_oarchive object in the main() function, so I only included the respective headers in the main. The rest of the code included the export.hpp header. So, I changed my common include file to also include the *archive.hpp headers and everything is working well.
The only thing that I've noticed is that sometimes the objects won't be found when I have 2 or more abstract classes between the base and the final concrete object. The concrete object is registered, but it looks like the (Derived,Base) pair isn't being found. Any advice on where I went wrong on that is appreciated. In the meantime, I'm using void_cast_register<>(...) to register the base class and the top derived class and everything works great so far :)
-Eric
On some compilers, one can get multiple symbol errors. I think the only way to handle this is to be sure its included at most once or tweak the linker switches to override the error.
Robert Ramey
"Eric" <eric-public@omnicurious.com> wrote in message news:001601c564d9$35709a60$0a00a8c0@FASTBRICK... Thanks Robert. This partially worked... Your comment about putting the BOOST_CLASS_EXPORT macro into the header keyed me into something.
I am using the BOOST_CLASS_EXPORT(derived) macro, but I've been placing them into the source (cpp) file instead of the header (h) file. With my system, when I put BOOST_CLASS_EXPORT(derived) into the header file, I get a multiply-defined error at link time (the offending code is boost::archive::detail::guid_initializer<class,...> since the header is included multiple times when I use the class.
As a test, I setup a sandbox with a stripped down system and was able to get it to work when I put the BOOST_CLASS_EXPORT in the header, but not when it is in the cpp file.
Q: Why does the location of the BOOST_CLASS_EXPORT matter? Is it doing order-depended initialization upon bringing up the system?
Q: How do I avoid the mutiple defined error in the linker?
Thanks again for your help and the library :)
-Eric