You may use config mode of the find_package for allow you modules to expose some internal properties to their user (root project).
If each your module provides
library target, you may expose that target with property containing Boost version attached and list this property in a special
COMPATIBLE_INTERFACE_STRING property.
Your root project will include modules via find_package() calls and will read these properties. When it will try to link libraries, provided by such modules, version compatibility will be automatically performed by CMake:
modA/CMakeLists.txt:
...
find_package(Boost)
add_library(modA_lib ...)
... # Link modA_lib with Boost
# Install modA_lib target and exports it for use in other project.
install(TARGETS modA_lib EXPORT modA_lib)
# Configured -config file is shown below
configure(modA-config.cmake.in modA-config.cmake)
install(EXPORT modA_lib
DESTINATION share/cmake/modA)
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/modA-config.cmake
DESTINATION share/cmake/modA)
modA/modA-config.cmake.in:
include(@CMAKE_INSTALL_PREFIX@/share/cmake/modA/modA_lib.cmake) # Include file described library target
# Expose linked version of Boost via target's property.
set_property(TARGET modA_lib PROPERTY INTERFACE_BOOST_VERSION @Boost_VERSION@)
# Mark this property as compatibility requirement
set_property(TARGET modA_lib PROPERTY APPEND COMPATIBLE_INTERFACE_STRING BOOST_VERSION)
(modB is implemented in similar manner)
root/CMakeLists.txt:
find_package(modA) # This imports target modA_lib
find_package(modB) # This imports target modB_lib
add_executable(root_exe <...>)
# Boost version check will be performed here
target_link_libraries(root_exe modA_lib modB_lib)
Additionally, an executable created in the root project may request specific Boost version via setting appropriate property:
add_executable(root_exe <...>)
set_property(TARGET root_exe PROPERTY BOOST_VERSION <...>)
In this case it will be prohibited (by CMake) for its dependencies to use Boost library with other versions.
More info and usage examples see in CMake build system
description.
