<br><tt><font size=2>"Yuri V. Timenkov" <ytimenkov@parallels.com>
wrote on 08/19/2008 03:26:34 PM:<br>
<br>
> On Tuesday 19 August 2008 17:10:56 Jos.van.den.Oever@panalytical.com
wrote:<br>
> > "Yuri V. Timenkov" <ytimenkov@parallels.com>
wrote on 08/19/2008 02:05:04<br>
> ><br>
> > PM:<br>
> > > Are following posts solve your problem?<br>
> > ><br>
> > > http://www.cmake.org/pipermail/cmake/2008-July/023099.html<br>
> > > http://www.cmake.org/pipermail/cmake/2006-September/011100.html<br>
> > > http://www.cmake.org/pipermail/cmake/2005-February/006080.html<br>
> ><br>
> > Yes they do. The tricky point was having to know that the symbol<br>
> > ${LIBRARYNAME}_EXPORTS is set when building the library.<br>
> > Then adding something along these lines in the header file solves
the<br>
> > problem:<br>
> ><br>
> > #ifdef _WIN32<br>
> > # ifdef testc2_EXPORTS<br>
> > # define WHATEVER __declspec( dllexport )<br>
> > # else<br>
> > # define WHATEVER __declspec( dllimport )<br>
> > # endif<br>
> > #else<br>
> > # define WHATEVER<br>
> > #endif<br>
> ><br>
> > WHATEVER float LibC2Func();<br>
> ><br>
> > So now I can get a simple project with one dll and one exe to
compile, but<br>
> > I still do not understand which program determines whether the
.exe should<br>
> > link to a .lib or a .dll. Does the Microsoft Visual Studio compiler<br>
> > determine this or does CMake inspect the header files?<br>
> > I find it strange that the linking command depends on the contents
of the<br>
> > header files. Is there a reason for this?<br>
> This is VS tricks. Studio generates 2 files: one import library (.<br>
> lib) and one <br>
> - dynamic library (.dll). gcc (and mingw family) exports all symbols
by <br>
> default, VS doesn't export anything by default. And if your dll doesn't
<br>
> export anything, VS simply doesn't generate import library (for example,
if <br>
> you generate resource-only dll). The only thing cmake knows is when
you using <br>
> VS generator, library extension to link with -- is .lib. And when
you use <br>
> __declspec( dllexport ), cl.exe puts special marks in objects indicating
that <br>
> this symbol should be exported or imported. Also, VS can tell linker
to add <br>
> some library, as it boost does with #pragma's.<br>
> <br>
> Really, this is well-known issue for VS developers ("Where is
my .lib file??? <br>
> >:-("), especially if you copy project and header files and
forgot change <br>
> defines. But because CMake makes migration to windows very smooth,
this <br>
> question appears near every month in this list as cmake on VS/Windows
newbie <br>
> question.<br>
</font></tt>
<br><tt><font size=2>Perhaps it's a idea to add an entry to http://www.cmake.org/Wiki/CMake_FAQ
then.</font></tt>
<br><tt><font size=2>Something that says: If there is no __declspec( dllexport
) in your header, only a dll and no lib is generated.</font></tt>
<br><tt><font size=2>CMake only tells the linker about the .lib, so if
__declspec( dllexport ) is not there linking fails even though there is
a .dll file.</font></tt>
<br>
<br><tt><font size=2>Thanks,</font></tt>
<br><tt><font size=2>Jos <br>
</font></tt><font size=2 face="Verdana"> <br>
<b><br>
Jos van den Oever </b>- SW Engineering <br>
</font>
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