More libalkimia problems/questions was: problems compiling 4.8 on system with both qt4 and qt5

[Christian David]

Hi Ralf,

I still do not like this. The reason is that this just fixes the symptom, not 
the problem. With these changes we make a huge technical dept. Exept for 
version 4.8 we solved nearly all problems mentioned here already. So all 
changes are only a workaround to enable coinstallablity with a 5 years old 
release (which got perfectly replaced by alkimia 5).

Also adding the version of Qt – a third party library – to the library sounds 
really strange to me. I am sure this will cause more issues in future.

Regarding packaging; if there is really a fine grained configuration needed,  
there are a lot of cmake variables like

CMAKE_SHARED_LIBRARY_SUFFIX [1]
LIBRARY_OUTPUT_PATH [2]
INCLUDEDIR [3]

and probably even more ECM variables to achive this. With them not a single 
line of alkimia has to be changed. The packager can tune everything just the 
way he wants to. This way, someone who just wants to compile alkimia does not 
need to learn our naming conventions.

I really want to get away from the idea to encode any kind of version in the 
library name.

Greetings
Christian


[1] 
https://cmake.org/cmake/help/v3.1/variable/CMAKE_SHARED_LIBRARY_SUFFIX.html
[2] https://cmake.org/cmake/help/v3.1/variable/LIBRARY_OUTPUT_PATH.html
[3] https://api.kde.org/ecm/kde-module/KDEInstallDirs.html?highlight=includedir

P.S.:
The code
> if(QT4_FOUND)
>    find_package(LibAalkimia4)
>    if(NOT LIBALKIMIA4_FOUND)
> 	find_package(LibAalkimia)
>    endif()
> else()
>    find_package(LibAalkimia5)
> endif()
> 
> if(QT4_FOUND)
>    set(QT_SLOT 4)
> else()
>    set(QT_SLOT 5)
> endif()
> 
> find_package(LibAalkimia${QT_SLOT})
> ...
> 
> |add_executable(<target> ...) target_link_libraries(<target>
> Alkimia::alkimia)

is way to long. find_package and the config scripts have the task to take such 
burdens of the package user. Probably the last line has to be changed from 
Alkimia::alkimia to Alkimia5::alkimia or so, too.


Am Mittwoch, 2. November 2016, 19:35:49 schrieb Ralf Habacker:
> Am 01.11.2016 um 00:05 schrieb Jack:
> > For Gentoo, if two versions are coinstallable, they get assigned to
> > different "slots" and in this case, I think the slot number would
> > easily correspond to the qt version (4 or 5) to align with other qt
> > and kde packages.  Also, as Gentoo is a source based distro, they
> > really cannot install any files with the same name, so the base
> > libalkimia.so should go to libalkimia4.so and libalkimia5.so.  (One of
> > them could stay libalkimia.so, but why not make things consistent if
> > were changing that much anyway?)
> 
> Collecting all requirements we get the following installation path layout:
> 
> Alikima 6.0.90 Qt4: [on a x86_64 system using /usr/local install prefix]
> -- Installing: /usr/local/lib64/libalkimia4.so.6.0.90
> -- Installing: /usr/local/lib64/libalkimia4.so.6
> -- Installing: /usr/local/lib64/libalkimia4.so
> -- Installing:
> /usr/local/lib64/cmake/LibAlkimia4-6.0/LibAlkimia4Targets.cmake --
> Installing:
> /usr/local/lib64/cmake/LibAlkimia4-6.0/LibAlkimia4Targets-noconfig.cmake --
> Installing: /usr/local/include/alkimia4-6.0/alkimia/alkvalue.h
> -- Installing: /usr/local/include/alkimia4-6.0/alkimia/alkquoteitem.h
> -- Installing: /usr/local/include/alkimia4-6.0/alkimia/alkcompany.h
> -- Installing: /usr/local/include/alkimia4-6.0/alkimia/alk_export.h
> -- Installing:
> /usr/local/lib64/cmake/LibAlkimia4-6.0/LibAlkimia4Config.cmake [1] --
> Installing:
> /usr/local/lib64/cmake/LibAlkimia4-6.0/LibAlkimia4ConfigVersion.cmake --
> Installing: /usr/local/lib64/cmake/LibAlkimia4-6.0/FindGMP.cmake --
> Installing: /usr/local/lib64/pkgconfig/libalkimia4.pc [2]
> 
> [1] with LIBALKIMIA4_INCLUDE_DIR=${PACKAGE_PREFIX_DIR}/include/alkimia4-6.0/
> and LIBALKIMIA4_LIBRARIES=${PACKAGE_PREFIX_DIR}/lib64/libalkimia4.so.6.0.90
> [2] with includedir=include/alkimia4-6.0 and Libs:-lalkimia4
> 
> Alkimia 6.0.90 Qt5:  [on a x86_64 system using /usr/local install prefix]
> -- Installing: /usr/local/lib64/libalkimia5.so.6.0.90
> -- Installing: /usr/local/lib64/libalkimia5.so.6
> -- Installing: /usr/local/lib64/libalkimia5.so
> -- Installing:
> /usr/local/lib64/cmake/LibAlkimia5-6.0/LibAlkimia5Targets.cmake --
> Installing:
> /usr/local/lib64/cmake/LibAlkimia5-6.0/LibAlkimia5Targets-noconfig.cmake --
> Installing: /usr/local/include/alkimia5-6.0/alkimia/alkvalue.h
> -- Installing: /usr/local/include/alkimia5-6.0/alkimia/alkquoteitem.h
> -- Installing: /usr/local/include/alkimia5-6.0/alkimia/alkcompany.h
> -- Installing: /usr/local/include/alkimia5-6.0/alkimia/alk_export.h
> -- Installing:
> /usr/local/lib64/cmake/LibAlkimia5-6.0/LibAlkimia5Config.cmake [1] --
> Installing:
> /usr/local/lib64/cmake/LibAlkimia5-6.0/LibAlkimia5ConfigVersion.cmake --
> Installing: /usr/local/lib64/cmake/LibAlkimia5-6.0/FindGMP.cmake --
> Installing: /usr/local/lib64/pkgconfig/libalkimia5.pc [2]
> 
> [1] with LIBALKIMIA5_INCLUDE_DIR=${PACKAGE_PREFIX_DIR}/include/alkimia5-6.0/
> and LIBALKIMIA5_LIBRARIES=${PACKAGE_PREFIX_DIR}/lib64/libalkimia5.so.6.0.90
> [2] with includedir=include/alkimia5-6.0 and Libs:-lalkimia5
> 
> 
> On the client side this would required to use
> 
> if(QT4_FOUND)
>    find_package(LibAalkimia4)
>    if(NOT LIBALKIMIA4_FOUND)
> 	find_package(LibAalkimia)
>    endif()
> else()
>    find_package(LibAalkimia5)
> endif()
> 
> if(QT4_FOUND)
>    set(QT_SLOT 4)
> else()
>    set(QT_SLOT 5)
> endif()
> 
> find_package(LibAalkimia${QT_SLOT})
> ...
> 
> |add_executable(<target> ...) target_link_libraries(<target>
> 
> Alkimia::alkimia)|
> 
> BTW: Using the '4' slot has also the advantage to not conflict with the
> present cmake find module for version 4.3.2 which already results in some
> detection issues.
> 
> If that is accepted I would provide a pull or review request for alkimia
> with a related patch.
> 
> Cheers
> Ralf