Cmake入门之——Set方法(六)

发表于 分类于 ， ， 阅读时长 ≈ 3 分钟

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