There's a slightly nicer work-around: Change project A's CMakeLists to set PROJB_OPENCV_LINK as a cache variable, ie, SET(PROJB_OPENCV_LINK NO CACHE BOOLEAN "doc"). I've tested it locally and it works the way you want it to.
It seems that CMake divides the world of variables into two classes: cache variables and non-cache variables. Somewhat unfortunately, the same function, SET(), is used to specify values for both kinds, and cache variables "hide" any non-cache variables with the same name. The upshot is that the same SET() command will do different things depending on what's currently in the cache. Further confusion here comes from the fact that when a variable is declared as a cache variable (using either option() or set(...CACHE...) ), any current value that the non-cache variable with the same name has is discarded. So the first time you run cmake, PROJB_OPENCV_LINK isn't a cache variable until it gets to processing projb's CMakeLists.txt, hence the non-cache value you provided gets dropped. The second time, it's already a cache variable, so project A's CMakeLists actually sets the cache variable, and therefore projb's CMakeLists sees it as you expect. It's definitely confusing, but I'm not totally sure what the right solution is. It probably would have been cleaner if CMake made the distinction clear between cache and non-cache variables, but it's far too late to change that now. Maybe it would be possible to change it such that a cache variable declaration (option() or set(...CACHE...) ) would allow a current non-cache variable of the same name to override the declaration's default value, in the same way that -D on the command-line does. Ceej aka Chris Hillery On Fri, Jul 2, 2010 at 2:52 PM, Gaspard Bucher <gasp...@teti.ch> wrote: > I have two projects: A and B. A depends on B but should set some settings > for the proper compilation of B when included in A. > > ==== CMakeLists.txt ==== (project A) > > set(PROJB_OPENCV_LINK NO) > > add_subdirectory(vendor/projb) > > ==== vendor/projb/CMakeLists.txt === (project B) > > option (PROJB_OPENCV_LINK "Set this to NO to link opencv alloc later." YES) > > ======== > > The local value "PROJB_OPENCV_LINK" is overwritten by the option on the > first run. If you run cmake a second time, the cached value is seen and > takes over so the option does not overwrite. > > I do not see any reason why an "option" setting should overwrite a defined > variable. > > build > cmake .. ==> fail > > build > cmake .. || cmake .. ==> works. This is absurd. > > Gaspard > > > PS: I know there is a workaround by using IF(DEFINED...). > > _______________________________________________ > Powered by www.kitware.com > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Follow this link to subscribe/unsubscribe: > http://www.cmake.org/mailman/listinfo/cmake >
_______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://www.cmake.org/mailman/listinfo/cmake