CMake和查找其他项目及其依赖项
设想以下情况：项目A是一个共享库，它有几个依赖关系（LibA，LibB，LibC）。 项目B是对项目A具有依赖性的可执行文件，因此也需要项目A的所有依赖项才能生成。
另外，这两个项目都是使用CMake构build的，不需要安装项目A（通过“安装”目标）以便项目B使用它，因为这对开发人员来说可能是一个麻烦。
所以问题是，使用CMake解决这些依赖问题的最好方法是什么？ 理想的解决scheme将尽可能简单（虽然不简单），并且需要最less的维护。
简单。 这是我头顶的例子：
顶级CMakeLists.txt ：
cmake_minimum_required(VERSION 2.8.10) # You can tweak some common (for all subprojects) stuff here. For example: set(CMAKE_DISABLE_IN_SOURCE_BUILD ON) set(CMAKE_DISABLE_SOURCE_CHANGES ON) if ("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}") message(SEND_ERROR "In-source builds are not allowed.") endif () set(CMAKE_VERBOSE_MAKEFILE ON) set(CMAKE_COLOR_MAKEFILE ON) # Remove 'lib' prefix for shared libraries on Windows if (WIN32) set(CMAKE_SHARED_LIBRARY_PREFIX "") endif () # When done tweaking common stuff, configure the components (subprojects). # NOTE: The order matters! The most independent ones should go first. add_subdirectory(components/B) # B is a static library (depends on Boost) add_subdirectory(components/C) # C is a shared library (depends on B and external XXX) add_subdirectory(components/A) # A is a shared library (depends on C and B) add_subdirectory(components/Executable) # Executable (depends on A and C)
CMakeLists.txt在components/B ：
cmake_minimum_required(VERSION 2.8.10) project(BC CXX) find_package(Boost 1.50.0 REQUIRED) file(GLOB CPP_FILES source/*.cpp) include_directories(${Boost_INCLUDE_DIRS}) add_library(${PROJECT_NAME} STATIC ${CPP_FILES}) # Required on Unix OS family to be able to be linked into shared libraries. set_target_properties(${PROJECT_NAME} PROPERTIES POSITION_INDEPENDENT_CODE ON) target_link_libraries(${PROJECT_NAME}) # Expose B's public includes (including Boost transitively) to other # subprojects through cache variable. set(${PROJECT_NAME}_INCLUDE_DIRS ${PROJECT_SOURCE_DIR}/include ${Boost_INCLUDE_DIRS} CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
CMakeLists.txt在components/C ：
cmake_minimum_required(VERSION 2.8.10) project(CC CXX) find_package(XXX REQUIRED) file(GLOB CPP_FILES source/*.cpp) add_definitions(${XXX_DEFINITIONS}) # NOTE: Boost's includes are transitively added through B_INCLUDE_DIRS. include_directories(${B_INCLUDE_DIRS} ${XXX_INCLUDE_DIRS}) add_library(${PROJECT_NAME} SHARED ${CPP_FILES}) target_link_libraries(${PROJECT_NAME} B ${XXX_LIBRARIES}) # Expose C's definitions (in this case only the ones of XXX transitively) # to other subprojects through cache variable. set(${PROJECT_NAME}_DEFINITIONS ${XXX_DEFINITIONS} CACHE INTERNAL "${PROJECT_NAME}: Definitions" FORCE) # Expose C's public includes (including the ones of C's dependencies transitively) # to other subprojects through cache variable. set(${PROJECT_NAME}_INCLUDE_DIRS ${PROJECT_SOURCE_DIR}/include ${B_INCLUDE_DIRS} ${XXX_INCLUDE_DIRS} CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
CMakeLists.txt在components/A ：
cmake_minimum_required(VERSION 2.8.10) project(AC CXX) file(GLOB CPP_FILES source/*.cpp) # XXX's definitions are transitively added through C_DEFINITIONS. add_definitions(${C_DEFINITIONS}) # NOTE: B's and Boost's includes are transitively added through C_INCLUDE_DIRS. include_directories(${C_INCLUDE_DIRS}) add_library(${PROJECT_NAME} SHARED ${CPP_FILES}) # You could need `${XXX_LIBRARIES}` here too, in case if the dependency # of A on C is not purely transitive in terms of XXX, but A explicitly requires # some additional symbols from XXX. However, in this example, I assumed that # this is not the case, therefore A is only linked against B and C. target_link_libraries(${PROJECT_NAME} B C) # Expose A's definitions (in this case only the ones of C transitively) # to other subprojects through cache variable. set(${PROJECT_NAME}_DEFINITIONS ${C_DEFINITIONS} CACHE INTERNAL "${PROJECT_NAME}: Definitions" FORCE) # Expose A's public includes (including the ones of A's dependencies # transitively) to other subprojects through cache variable. set(${PROJECT_NAME}_INCLUDE_DIRS ${PROJECT_SOURCE_DIR}/include ${C_INCLUDE_DIRS} CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
components/Executable CMakeLists.txt ：
cmake_minimum_required(VERSION 2.8.10) project(Executable C CXX) file(GLOB CPP_FILES source/*.cpp) add_definitions(${A_DEFINITIONS}) include_directories(${A_INCLUDE_DIRS}) add_executable(${PROJECT_NAME} ${CPP_FILES}) target_link_libraries(${PROJECT_NAME} AC)
为了说清楚，这里是相应的源码树结构：
Root of the project ├───components │ ├───Executable │ │ ├───resource │ │ │ └───icons │ │ ├───source | | └───CMakeLists.txt │ ├───A │ │ ├───include │ │ │ └───A │ │ ├───source | | └───CMakeLists.txt │ ├───B │ │ ├───include │ │ │ └───B │ │ ├───source | | └───CMakeLists.txt │ └───C │ ├───include │ │ └───C │ ├───source | └───CMakeLists.txt └───CMakeLists.txt
有很多点可以调整/定制或改变，以满足某些需求，但这至less应该让你开始。
注意：我已经在几个大中型项目中成功地使用了这个结构。
