CMake set variables before defined, access them after being defined - cmake

Question

Is it possible to set a bunch of variables before they are defined e.g., when using CUDA and I write
SET(MY_CUDA_LIBS CUDA_CUBLAS_LIBRARIES CUDA_CUFFT_LIBRARIES),
such that when are being defined by
FIND_PACKAGE(CUDA REQUIRED)
(CUDA_CUBLAS_LIBRARIES and CUDA_CUFFT_LIBRARIES can now be accessed i.e., ${CUDA_CUBLAS_LIBRARIES} and ${CUDA_CUFFT_LIBRARIES} are the paths to the corresponding library), I can access something like ${MY_CUDA_LIBS} and it returns ${CUDA_CUBLAS_LIBRARIES} ${CUDA_CUFFT_LIBRARIES}?
This obviously works, if I e.g. use CUDA_CUBLAS_LIBRARIES only and do ${${MY_CUDA_LIBS}}, but as soon as one has multiple libraries this trick does not work anymore and it returns CUDA_CUBLAS_LIBRARIESCUDA_CUFFT_LIBRARIES or "nothing".
The idea is to define the CUDA libraries in the very beginning of my CMakeLists.txt and it (far) later automatically inserts the corresponding path when accessed in TARGET_LINK_LIBRARIES.

Answer 1

Technically, you should treat the MY_CUDA_LIBS as a list. Then, the following is possible:
set(MANY_LIBS LIB_1 LIB_2)
set(LIB_1 "/libs/lib1")
set(LIB_2 "/libs/lib2")
list(GET MANY_LIBS 0 PATH)
message(${${PATH}})
list(GET MANY_LIBS 1 PATH)
message(${${PATH}})
resulting in the following output as predicted:
/libs/lib1
/libs/lib2
If you want it to use later in TARGET_LINK_LIBRARIES you probably can do the following after your variable are defined properly:
foreach(libname ${MANY_LIBS})
list(APPEND MANY_LIBS_PATHS ${${libname}})
endforeach(${MANY_LIBS_PATHS})
message("${MANY_LIBS_PATHS}")
after that, MANY_LIBS_PATHS can be used for linking.