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一 概述

set方法是cmake-commands中的脚本方法，用于给下面的变量设置值：

• 一般变量(Set Normal Variable)
• 缓存变量(Set Cache Entry)
• 环境变量(Set Environment Variable)

二 Set方法说明

2.1 一般变量(Set Normal Variable)

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set(<variable> <value>... [PARENT_SCOPE])

• variable：只能有一个
• value：可以有0个，1个或多个，当value值为空时，方法同unset，用于取消设置的值
• PARENT_SCOPE(父作用域)：作用域，除PARENT_SCOPE外还有function scope(方法作用域)和directory scope(目录作用域)

2.2 缓存变量(Set Cache Entry)

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set(<variable> <value>... CACHE <type> <docstring> [FORCE])

• variable：只能有一个
• value：可以有0个，1个或多个，当value值为空时，方法同unset，用于取消设置的值
• CACHE：关键字，说明是缓存变量设置
• type(类型)：必须为以下中的一种：
  • BOOL：有ON/OFF，两种取值
  • FILEPATH：文件的全路径
  • PATH：目录路径
  • STRING：字符串
  • INTERNAL：字符串
• docstring：总结性文字(字符串)
• [FORCE]：变量名相同，第二次调用set方法时，第一次的value将会被覆盖

2.3 环境变量(Set Environment Variable)

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set(ENV{<variable>} [<value>])

• variable：只能有一个
• value：一般来说，只有一个，为空时，将清除之前设置的变量值，多个时，取值最近的一个，之后的值将被忽略

三 示例

3.1 一般变量(Set Normal Variable)

• CMakeLists.txt中设置

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  #normal set(normal "normalValue") message(WARNING ${normal}) set(a 1 b 2 "c" [PARENT_SCOPE]) message(WARNING ${a})

• Debug输出结果

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  CMake Warning at CMakeLists.txt:10 (message): normalValue CMake Warning at CMakeLists.txt:12 (message): 1b2c[PARENT_SCOPE]

3.2 缓存变量(Set Cache Entry)

• CMakeLists.txt中设置

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  # cache set(isOn ON CACHE BOOL "Bool" [FORCE]) message(WARNING ${isOn}) set(isOFF OFF CACHE BOOL "Bool" ) message(WARNING ${isOFF}) ## cache-FILEPATH set(filePath ${PROJECT_SOURCE_DIR}/CMakeLists.txt CACHE FILEPATH "file path") message(WARNING ${filePath}) set(filePath ${PROJECT_SOURCE_DIR}/main.cpp CACHE FILEPATH "file path" [FORCE]) message(WARNING ${filePath}) ## cache-PATH set(path ${PROJECT_SOURCE_DIR} CACHE PATH "path") message(WARNING ${path}) set(path ${PROJECT_BINARY_DIR} CACHE PATH "path" [FORCE]) message(WARNING ${path}) ## cache-STRING set(string cmake CACHE STRING "string") message(WARNING ${string}) set(string newcmake CACHE STRING "newstring" [FORCE]) message(WARNING ${string}) ##cache-internal set(internal internal CACHE INTERNAL "internal") message(WARNING ${internal}) set(internal newinternal CACHE INTERNAL "newinternal" [FORCE]) message(WARNING ${internal})

• Debug输出结果

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  CMake Warning at CMakeLists.txt:12 (message): ONCACHEBOOLBool[FORCE] CMake Warning at CMakeLists.txt:14 (message): OFF CMake Warning at CMakeLists.txt:18 (message): E:/Code/ClionDemo/CmakeSet/CMakeLists.txt CMake Warning at CMakeLists.txt:20 (message): E:/Code/ClionDemo/CmakeSet/main.cppCACHEFILEPATHfile path[FORCE] CMake Warning at CMakeLists.txt:24 (message): E:/Code/ClionDemo/CmakeSet CMake Warning at CMakeLists.txt:26 (message): E:/Code/ClionDemo/CmakeSet/cmake-build-debugCACHEPATHpath[FORCE] CMake Warning at CMakeLists.txt:30 (message): cmake CMake Warning at CMakeLists.txt:32 (message): newcmakeCACHESTRINGnewstring[FORCE] CMake Warning at CMakeLists.txt:36 (message): internal CMake Warning at CMakeLists.txt:38 (message): newinternalCACHEINTERNALnewinternal[FORCE]

3.3 环境变量(Set Environment Variable)

• CMakeLists.txt中设置

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  message(WARNING $ENV{JAVA_HOME}) #JAVA_HOME是windows中设置的变量 set(ENV{JAVA_HOME} 1) message(WARNING $ENV{JAVA_HOME}) set(ENV{DEFINE} DEFINE DEFINE2 DEFINE3) #自定义的变量 message(WARNING $ENV{DEFINE}) set(a) #没有value值，a值清空 message(WARNING ${a})

• Debug输出结果

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  CMake Warning at CMakeLists.txt:42 (message): D:\SoftWare\Java\jdk1.8.0_191 CMake Warning at CMakeLists.txt:44 (message): 1 CMake Warning at CMakeLists.txt:49 (message): DEFINE CMake Warning at CMakeLists.txt:52 (message):

四 参考

• 
  Documentation>>cmake-command>>set