CMake配置从根目录或子目录构建项目

我最近开始使用CMake（2.8.12.2，CentOS 6.8中包含的一个），我认为它足够强大，可以帮助我完成我想要的，但我还没有弄清楚如何：-），因此我呼吁您的智慧帮助我找到缺失的一点

我的项目布局如下：

BaseDir
|
+-->bin (generated by the process)
|    |
|    +-->Debug
|    +-->Release
|
+-->lib (generated by the process)
|    |
|    +-->Debug
|    +-->Release
|    
+-->CMakeLists.txt
|
+-->Library_A
|    |
|    +-->CMakeLists.txt
|    +-->include
|    +-->src
|    |    |
|    |    +-->CMakeLists.txt
|    |
|    +-->test # Small binary to test solely the library functions 
|        |
|        +-->CMakeLists.txt
|
+-->Library_B (depends on Library_A)
|    |
|    +-->CMakeLists.txt
|    +-->include
|    +-->src
|    |    |
|    |    +-->CMakeLists.txt
|    |
|    +-->test # Small binary to test solely the library functions 
|        |
|        +-->CMakeLists.txt
|
+-->Application_1 (depends on Library_B, hence transitivitely depends on Library_A)
|    |
|    +-->CMakeLists.txt
|    +-->include
|    +-->src
|        |
|        +-->CMakeLists.txt
|
+-->Application_2 (depends on Library_A)
    |
    +-->CMakeLists.txt
    +-->include
    +-->src
        |
        +-->CMakeLists.txt

当我把自己放在BaseDir下运行“cmake”时，它就像一个符咒。应用程序1、应用程序2、库A和库B都以正确的顺序构建、链接等

然而，我的想法是能够在任何子目录（Application、Library）下进行构建，在这种情况下，只构建与之相关的代码（即它本身、它的测试和它的依赖项）。例如，当站在库_A中时，仅生成该文件夹，而从库_B中也生成库_A，以及在应用程序_1或应用程序_2下发生的等效情况。另外，在触发cmake进程的位置上，构建结果（lib或bin）必须始终放在BaseDir/{lib|bin}/{Debug/Release/etc}下，而不能放在库或应用程序子目录下。例如，它意味着库_B（依赖于库_A）或应用程序_1（依赖于库_A和B）的链接必须查看BaseDir/lib/{Debug/Release}

我的目标是在BaseDir下有许多应用程序，所以如果不是真的需要，我希望避免每次都要构建它们，只构建我想要的单个应用程序

我也研究过，但这与我在这里试图实现的情况并不完全相同

我尝试过以下方法：

BaseDir/CMakeLists.txt
|
|    cmake_minimum_required (VERSION 2.8)
|    project (BASE_DIR)
|
|    add_subdirectory (Library_A)     # No local dependencies
|    add_subdirectory (Library_B)     # Depends on A
|    add_subdirectory (Application_1) # Depends on A and B
|    add_subdirectory (Application_2) # Depends on A
|
|    # I want all binary outputs (executables and libraries) placed under BaseDir/{lib|bin}/{Debug|Release}
|    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/bin/${CMAKE_BUILD_TYPE}") # For the executables
|    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/lib/${CMAKE_BUILD_TYPE}") # For the static libraries
|    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/lib/${CMAKE_BUILD_TYPE}") # For the dynamic libraries
|
+-->BaseDir/Library_A/CMakeLists.txt (again, no dependencies)
|    |
|    |    cmake_minimum_required (VERSION 2.8)
|    |    project (LIB_A)
|    |    
|    |    # In case CMake is run from within BaseDir/Library_A and not from BaseDir, I still want the outputs being placed under BaseDir/{lib|bin}/{Debug|Release}
|    |    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../bin/${CMAKE_BUILD_TYPE}") # For the test executables
|    |    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../lib/${CMAKE_BUILD_TYPE}") # For the static libraries
|    |    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../lib/${CMAKE_BUILD_TYPE}") # For the dynamic libraries
|    |
|    |    include_directories(include)
|    |    add_subdirectory (src)
|    |    add_subdirectory (test)
|    |    set(${PROJECT_NAME}_INCLUDE_DIRECTORIES ${PROJECT_SOURCE_DIR}/include CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
|    |
|    +-->BaseDir/Library_A/src/CMakeLists.txt
|    |
|    |        cmake_minimum_required (VERSION 2.8)
|    |
|    |        # add all files in the current directory
|    |        file(GLOB LIB_A_SRCS "*.h" "*.cpp")
|    |
|    |        # Create a library called libA.a
|    |        add_library(A ${LIB_A_SRCS})
|    |
|    +-->BaseDir/Library_A/test/CMakeLists.txt
|    
|            cmake_minimum_required (VERSION 2.8)
|    
|            # add all files in the current directory
|            file(GLOB TEST_A_SRCS "*.h" "*.cpp")
|    
|            # Create an executable file from sources
|            add_executable(TEST_A ${TEST_A_SRCS})
|    
|            # Link this executable to the library it's testing
|            target_link_libraries(TEST_A A)
|    
+-->BaseDir/Library_B/CMakeLists.txt (dependency on A)
|    |    
|    |    cmake_minimum_required (VERSION 2.8)
|    |    project (LIB_B)
|    |    
|    |    # In case CMake is run from within BaseDir/Library_B and not from BaseDir, I still want the outputs being placed under BaseDir/{lib|bin}/{Debug|Release}
|    |    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../bin/${CMAKE_BUILD_TYPE}") # For the test executables
|    |    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../lib/${CMAKE_BUILD_TYPE}") # For the static libraries
|    |    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../lib/${CMAKE_BUILD_TYPE}") # For the dynamic libraries
|    |
|    |    include_directories(include)
|    |    add_subdirectory (src)
|    |    add_subdirectory (test)
|    |    set(${PROJECT_NAME}_INCLUDE_DIRECTORIES ${PROJECT_SOURCE_DIR}/include CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
|    |
|    +-->BaseDir/Library_B/src/CMakeLists.txt
|    |
|    |        cmake_minimum_required (VERSION 2.8)
|    |
|    |        # add all files in the current directory
|    |        file(GLOB LIB_B_SRCS "*.h" "*.c")
|    |
|    |        # Create a library called libB.a
|    |        add_library(B ${LIB_B_SRCS})
|    |        
|    |        # Add a dependency to Library_A
|    |        find_library(LIBRARY_A A PATHS ${CMAKE_CURRENT_SOURCE_DIR}/../../Library_A)
|    |        include_directories("$LIB_A_INCLUDE_DIRECTORIES")
|    |        target_link_libraries(B ${LIBRARY_A}) 
|    |
|    +-->BaseDir/Library_B/test/CMakeLists.txt
|
|            cmake_minimum_required (VERSION 2.8)
|
|            # add all files in the current directory
|            file(GLOB TEST_B_SRCS "*.h" "*.cpp")
|
|            # Create an executable file from sources, for both versions of the library
|            add_executable(TEST_B ${TEST_B_SRCS})
|            
|            # Link this executable to the library it's testing
|            target_link_libraries(TEST_B B)
|
+-->BaseDir/Application_1/CMakeLists.txt
|    |
|    |    cmake_minimum_required (VERSION 2.8)
|    |    project (APP_1)
|    |    
|    |    # In case CMake is run from within BaseDir/Application_1 and not from BaseDir, I still want the outputs being placed under BaseDir/{lib|bin}/{Debug|Release}
|    |    # In this case, only executables are generated.
|    |    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../bin/${CMAKE_BUILD_TYPE}")
|    |
|    |    include_directories(include)
|    |    add_subdirectory (src)
|    |
|    +-->BaseDir/Application_1/src/CMakeLists.txt
|
|            cmake_minimum_required (VERSION 2.8)
|
|            # add all files in the current directory
|            file(GLOB APP_1_SRCS "*.cpp")
|
|            # Create an executable file from sources
|            add_executable(EXE_1 ${APP_1_SRCS})
|            
|            # This should automatically bring Library_A
|            find_library(LIBRARY_B B PATHS ${CMAKE_CURRENT_SOURCE_DIR}/../../Library_B)
|            include_directories(${LIB_B_INCLUDE_DIRECTORIES})
|            target_link_libraries(EXE_1 ${LIBRARY_B})
|
+-->BaseDir/Application_2/CMakeLists/CMakeLists.txt
    |
    |    cmake_minimum_required (VERSION 2.8)
    |    project (APP_2)
    |    
    |    # In case CMake is run from within BaseDir/Application_2 and not from BaseDir, I still want the outputs being placed under BaseDir/{lib|bin}/{Debug|Release}
    |    # In this case, only executables are generated.
    |    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/../bin/${CMAKE_BUILD_TYPE}")
    |
    |    include_directories(include)
    |    add_subdirectory (src)
    |
    +-->BaseDir/Application_2/src/CMakeLists.txt

            cmake_minimum_required (VERSION 2.8)

            # add all files in the current directory
            file(GLOB APP_2_SRCS "*.cpp")

            # Create an executable file from sources
            add_executable(EXE_2 ${APP_2_SRCS})

            # Link this executable to the library it needs
            find_library(LIBRARY_A A PATHS ${CMAKE_CURRENT_SOURCE_DIR}../../Library_A)
            include_directories(${LIB_A_INCLUDE_DIRECTORIES})
            target_link_libraries(EXE_2 ${LIBRARY_A})

但是没有运气，因为当我从子目录（例如，BaseDir/Application_1）运行时，我只得到：

CMake错误：此项目中使用了以下变量，但它们被设置为NOTFOUND。 请设置或确保在CMake文件中正确设置和测试： 图书馆

我想，“find_library（）”调用不足以满足我的需要，这基本上是加载libraries项目中包含的所有设置，不仅包括库本身，还包括该库添加的include目录。find_library（）的具体用法是什么，将它指向创建库的项目的位置，或实际生成的库（“.a”或“.so”）

所以，我的主要疑问是：这种布局可行吗？如果是，我错过了什么？我是否应该使用类似于查找包（）或查找路径（）的方法？如何从另一个“相同级别”CMakeLists.txt触发对CMakeLists.txt配置文件的解析

---

PS：我真的需要考虑在任何时候使用<强>“AddiSuffiCeCes（）”<强>吗？如果没有，该命令的意义何在？

首先是一条一般性建议：在CMake中，您将始终希望尝试严格地将构建目录与源目录分开。尤其是，在构建过程中，不应将文件写回源目录。编写脚本，以便它们也能与装载在只读文件系统上的源目录一起工作。虽然一开始这看起来像是一个任意的限制，但从长远来看，它实际上会帮助您避免许多麻烦

至于您的实际问题：

find_library

是解决依赖性问题的非常低级的工具。这里的想法基本上是，您在系统的某个地方安装了第三方库的二进制文件（该库本身对CMake一无所知），您知道只需检查文件系统的内容就可以找到它们。这里的情况并非如此，因为您将依赖项构建为同一CMake配置运行的一部分

相反，您要做的是直接依赖于依赖项的目标。因此，与其这样做，不如：

find_library(LIBRARY_A A)
target_link_libraries(B ${LIBRARY_A}) 

你会直接写信吗

target_link_libraries(B A)

当然，只有当

A

是当时已知的目标时，这才有效，这是您应该关注的问题

只要您在同一个CMake运行中一起构建库，这是非常简单的：如果目标是由父目录或同级目录添加的，您应该能够立即使用它。在您的情况下，使事情复杂化的是，您还希望能够独立地构建不同的库。这意味着您需要一种机制，将目标导入到您的构建中，使其看起来像是作为同一个CMake运行的一部分再次生成的目标

---

您可以通过添加并设置其接口属性手动执行此操作，也可以使用CMake以自动方式执行此操作。请注意，这两项都不是小事，因此，您可能希望从一个简单的案例开始，在一次CMake运行中完成所有操作，然后在您更熟悉使用CMake之后添加对分离构建的支持。

首先，一条一般性建议：在CMake中，您将始终希望尝试严格地将构建目录与源目录分离。尤其是，在构建过程中，不应将文件写回源目录。编写脚本，以便它们也能与装载在只读文件系统上的源目录一起工作。虽然一开始这看起来像是一个任意的限制，但从长远来看，它实际上会帮助您避免许多麻烦

至于您的实际问题：

find_library

是解决依赖性问题的非常低级的工具。这里的想法基本上是，您在系统的某个地方安装了第三方库的二进制文件（该库本身对CMake一无所知），您知道只需检查文件系统的内容就可以找到它们。这里的情况并非如此，因为您将依赖项构建为同一CMake配置运行的一部分

你想做的是直接