Re: [boost] [serialization] BOOST_CLASS_EXPORT in a separate staticlibrary

From: Hugh Hoover (hugh_at_[hidden])
Date: 2006-02-24 18:16:29

> Marcin Kalicinski wrote:
>> I noticed strange behavior of serialization on VC 8.0. I use
>> BOOST_CLASS_EXPORT macro in a .cpp file to register a derived class,
>> so that it can be properly serialized through base class pointer.
>> This works fine, as long the .obj file resulting from compilation  
>> of .cpp
>> file which
>> uses BOOST_CLASS_EXPORT macro is linked directly to the final
>> executable. But when I first put this .obj file into a static  
>> library, and
>> then link
>> the library to executable, I start getting unregistered_class
>> exceptions - as if there was no BOOST_CLASS_EXPORT invoked.

I'm having what appears to be a similar problem, although I can't get  
the BOOST_CLAS_EXPORT to work at all.  I have to use the  
ar.register_type form in order to get anything to work with derived  
classes.  (Also, i'm using gcc4)

Note that (at least so far) ALL of my serialization code is within a  
single file (that is, the code that actually does an "oa << foo", so  
that code was able to see all appropriate declarations and the  
BOOST_CLASS_EXPORT.

Any thoughts on that?

On Feb 23, 2006, at 18:22, Robert Ramey wrote:
> I recommend puting BOOST_CLASS_EXPORT in the header rather
> than in the *.cpp file.  The same goes for all serialization traits.
> Generally
> a class should be loaded with the same traits as when it is saved.   
> Putting
> traits in the header assures this to be the case.
>
> Robert Ramey

This just doesn't seem right to me - I had thought that  
BOOST_CLASS_EXPORT actually registered the appropriate type  
information globally, so that the ar.register_type calls wouldn't be  
required.  The extended_type_info class appears to contain a map that  
could be used for such.  As such, there shouldn't be any reason to  
have the EXPORT globally visible (and that introduces a problem for  
MY code).

I'm clearly not understanding something here, can someone enlighten me?

Hugh Hoover
Enumclaw Software