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List:       kde-devel
Subject:    Re: Custom EXPORT macro won't expand when included outside lib
From:       Sandro Andrade <sandroandrade () kde ! org>
Date:       2012-09-12 23:10:13
Message-ID: CAAnOZvXwfeU3+ocaDDYjJ9qDiOQV8sayhZazAzVpWxzCCnd=bA () mail ! gmail ! com
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On Wed, Sep 12, 2012 at 7:13 PM, Luiz Romário Santana Rios
<luizromario@gmail.com> wrote:
> 2012/9/11 Sandro Andrade <sandroandrade@kde.org>:
> > On Mon, Sep 10, 2012 at 9:29 PM, Luiz Romário Santana Rios
> > <luizromario@gmail.com> wrote:
> > > Hi.
> > > 
> > > So, I recently started to write a "pluggable" library. You can check it from
> > > here:
> > > http://quickgit.kde.org/index.php?p=scratch%2Fromariorios%2Flibkodri.git&a=summary
> > >                 
> > > .
> > > 
> > > It was all good until I tried to write a dummy plugin for it (currently
> > > available in the dummy_packagesource branch of the above repo). It was a
> > > pretty trivial plugin, it just implemented the pure virtual functions from
> > > the interface. But I kept getting this error:
> > > 
> > > [100%] Building CXX object
> > > packagesources/CMakeFiles/kodri_packagesource_dummy.dir/dummypackagesource.o
> > > In file included from
> > > /home/kde4/kde-master-install/include/kodri/abstractpackagesource.h:29:0,
> > > from
> > > /home/kde4/kdesrc/libkodri/packagesources/dummypackagesource.h:23,
> > > from
> > > /home/kde4/kdesrc/libkodri/packagesources/dummypackagesource.cpp:20:
> > > /home/kde4/kde-master-install/include/kodri/version.h:31:28: error: expected
> > > initializer before ‘:’ token
> > > /home/kde4/kdesrc/libkodri/packagesources/dummypackagesource.cpp:1381:1:
> > > error: expected ‘}’ at end of input
> > > make[2]: **
> > > [packagesources/CMakeFiles/kodri_packagesource_dummy.dir/dummypackagesource.o]
> > > Erro 1
> > > make[1]: ** [packagesources/CMakeFiles/kodri_packagesource_dummy.dir/all]
> > > Erro 2
> > > make: ** [all] Erro 2
> > > 
> > > I then suspected that the KODRI_EXPORT macro wasn't being expanded when the
> > > exported classes were included outside the library. Then I manually replaced
> > > KODRI_EXPORT by __attribute__ ((visibility("default")) and, as I suspected,
> > > the error vanished. Of course, other errors appeared afterwards, but I'll
> > > try to solve them later.
> > > 
> > > My question is: why doesn't the macro expand? I followed the techbase
> > > tutorial on creating new libraries step by step, so I can't see where I got
> > > it wrong.
> > 
> > It doesn't expand because you have a wrong kodri_export.h:
> > 
> > #ifndef KODRI_EXPORT
> > # if defined(MAKE_KODRI_LIB)
> > #  define KODRI_EXPORT KDE_EXPORT
> > # else
> > #  define KODRI_IMPORT KDE_IMPORT
> > # endif
> > #endif
> > 
> > It should be:
> > 
> > #ifndef KODRI_EXPORT
> > # if defined(MAKE_KODRI_LIB)
> > #  define KODRI_EXPORT KDE_EXPORT
> > # else
> > #  define KODRI_EXPORT KDE_IMPORT
> > # endif
> > #endif
> Whoops...
> 
> Thank you, I'd take ages to notice that.
> 
> > 
> > Besides that, I'd rearrange CMakeLists.txt's in order to have lib and
> > plugin as sibling sub-CMakeLists.txt (or even as separated projects).
> > Find a possible refactoring at:
> > 
> > http://d01.megashares.com/dl/dTjbpUz/libkodri-refactored.tar.gz
> I'll take a look at it.
> 
> > 
> > Plugin's CMakeLists.txt also contains some errors:
> > 
> > target_link_libraries(kodri_packagesource_dummy ${KDE4_CORE_LIBS}
> > ${KDE4_KODRI_LIBS})
> > 
> > The correct var is ${KDE4_KDECORE_LIBS}. ${KDE4_KODRI_LIBS} isn't
> > automatically generated
> > at all. You should write a cmake module in order to detect your library.
> I have this in CMakeLists.txt:37:
> 
> install(TARGETS kodri EXPORT kdelibsLibraryTargets
> ${INSTALL_TARGETS_DEFAULT_ARGS})
> 
> Doesn't it do the job?

Not completely. If you try to build the plugin in an environment which
doesn't have your
lib installed, cmake won't detect that. You'll get only a compiler error.

See for example:
https://projects.kde.org/projects/extragear/kdevelop/kdevelop/repository/revisions/master/entry/cmake/modules/FindKDevPlatform.cmake


That will allow you to use a:

find_package(Kodri 1.0.0 REQUIRED)

in the plugin's CMakeLists.txt. If it's not found cmake will early detect that.

[]s,
Sandro

> 
> Thanks for the pointers.
> 
> > 
> > Sandro
> > 
> > > 
> > > Best regards.
> > > 
> > > --
> > > Luiz Romário Santana Rios
> > > 
> > > 
> > > > > Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe
> > > > > <<
> > > 
> > 
> > > > Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<
> 
> 
> 
> --
> Luiz Romário Santana Rios
> 
> > > Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<

> > Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<


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