Re: Windows linking problem

[Bruce D. <bru...@gm...>]

Thank you *very* much.  It looks like defining QWT_DLL solved the 
problem.  I have a fairly complex structure:

   my library A uses
     my library B (no gui elements)
     qwt

I did not have  the __declspec() in my class and it is needed, but I 
also did not include the QWT_DLL define in my .pro file.  Now that they 
are defined, it looks like I'm in business.

I still have several problems related to __declspec(), but now I have a 
path to solve them.

Thanks again.

   -- Bruce


David Stranz wrote:
> Bruce,
> 
> Check again your C++ and linker options for QWT_DLL and other Qwt 
> defines.  What you have described is exactly what I would expect to see.
> 
> Qwt classes are declared with a "QWT_EXPORT" modifier, which maps to 
> some Microsoft __declspec() gibberish depending on the definition of 
> Qwt_DLL.  When you derive a class from a Qwt QObject-based class, you 
> drag that in.  If you derive from a non-Qwt QObject class, that modifier 
> isn't involved.
> 
> I think what you're seeing is a mismatch between Qwt built with one 
> version of the QWT_DLL declaration, and one or more of your modules 
> built with a different one.
> 
> I've see this before, and always has to do with a mismatch between Qwt 
> defines in linkage units.
> 
> David
> 
> _______________________________________________________________
> David Stranz, Ph.D.	david_stranz@MassSpec.com