原文地址: https://blog.csdn.net/dbzhang800/article/details/6341029
在Cmake学习笔记三 中简单学习了 find_package 的 model 模式，在Cmake学习笔记四 中了解一个CMakeCache相关的东西。但靠这些知识还是不能看懂PySide使用CMakeLists文件，接下来继续学习find_package的 config 模式及package configure文件相关知识
当CMakeLists.txt中使用find_package命令时，首先启用的是 module 模式：
- 按照 CMAKE_MODULE_PATH 路径和cmake的安装路径去搜索finder文件 Find<package>.cmake
如果finder未找到，则开始 config 模式：
- 将在下列路径下查找 配置 文件 <name>Config.cmake 或 <lower-case-name>-config.cmake
| <prefix>/ | (W) |
| <prefix>/(cmake|CMake)/ | (W) |
| <prefix>/<name>*/ | (W) |
| <prefix>/<name>*/(cmake|CMake)/ | (W) |
| <prefix>/(share|lib)/cmake/<name>*/ | (U) |
| <prefix>/(share|lib)/<name>*/ | (U) |
| <prefix>/(share|lib)/<name>*/(cmake|CMake)/ | (U) |
- find_package 参数及规则见manual
该文件至少需提供头文件路径和库文件信息。比如 ApiExtractorConfig.cmake 在Windows下一个例子：
# - try to find APIEXTRACTOR
# APIEXTRACTOR_INCLUDE_DIR - Directories to include to use APIEXTRACTOR
# APIEXTRACTOR_LIBRARIES - Files to link against to use APIEXTRACTOR
SET(APIEXTRACTOR_INCLUDE_DIR "D:/shiboken/dist/include/apiextractor")
if(MSVC)
SET(APIEXTRACTOR_LIBRARY "D:/shiboken/dist/lib/apiextractor.lib")
elseif(WIN32)
SET(APIEXTRACTOR_LIBRARY "D:/shiboken/dist/bin/apiextractor.dll")
else()
SET(APIEXTRACTOR_LIBRARY "D:/shiboken/dist/lib/apiextractor.dll")
endif()
该文件是通过 configure_file 机制生成的，我们看看 ApiExtractorConfig.cmake.in 文件：
SET(APIEXTRACTOR_INCLUDE_DIR "@CMAKE_INSTALL_PREFIX@/include/apiextractor@apiextractor_SUFFIX@")
if(MSVC)
SET(APIEXTRACTOR_LIBRARY "@LIB_INSTALL_DIR@/@CMAKE_SHARED_LIBRARY_PREFIX@apiextractor@apiextractor_SUFFIX@@LIBRARY_OUTPUT_SUFFIX@.lib")
elseif(WIN32)
SET(APIEXTRACTOR_LIBRARY "@CMAKE_INSTALL_PREFIX@/bin/@CMAKE_SHARED_LIBRARY_PREFIX@apiextractor@apiextractor_SUFFIX@@LIBRARY_OUTPUT_SUFFIX@@CMAKE_SHARED_LIBRARY_SUFFIX@")
else()
SET(APIEXTRACTOR_LIBRARY "@LIB_INSTALL_DIR@/@CMAKE_SHARED_LIBRARY_PREFIX@apiextractor@apiextractor_SUFFIX@@LIBRARY_OUTPUT_SUFFIX@@CMAKE_SHARED_LIBRARY_SUFFIX@")
endif()
对应的命令(变量的定义略过)
configure_file("${CMAKE_CURRENT_SOURCE_DIR}/ApiExtractorConfig.cmake.in" "${CMAKE_CURRENT_BINARY_DIR}/ApiExtractorConfig.cmake" @ONLY)
该文件用来比对版本是否匹配，看看ApiExtractorConfigVersion.cmake.in 的内容：
set(PACKAGE_VERSION @apiextractor_VERSION@)
if("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}" )
set(PACKAGE_VERSION_COMPATIBLE FALSE)
else("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}" )
set(PACKAGE_VERSION_COMPATIBLE TRUE)
if( "${PACKAGE_FIND_VERSION}" STREQUAL "${PACKAGE_VERSION}")
set(PACKAGE_VERSION_EXACT TRUE)
endif( "${PACKAGE_FIND_VERSION}" STREQUAL "${PACKAGE_VERSION}")
endif("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}" )
一般提供设置下面的变量
| PACKAGE_VERSION | 完整的版本字符串 |
| PACKAGE_VERSION_EXACT | 如果完全匹配为真 |
| PACKAGE_VERSION_COMPATIBLE | 如果兼容为真 |
| PACKAGE_VERSION_UNSUITABLE | 如果不可用为真 |
find_package进而根据这些设置
| <package>_VERSION | full provided version string |
| <package>_VERSION_MAJOR | major version if provided, else 0 |
| <package>_VERSION_MINOR | minor version if provided, else 0 |
| <package>_VERSION_PATCH | patch version if provided, else 0 |
| <package>_VERSION_TWEAK | tweak version if provided, else 0 |
