目录
- CMake语法—选项（option）
- 1 选项
- 1.1 定义
- 1.2 说明
- 2 应用注意事项
- 2.1 代码结构
- 2.2 注意事项
- 2.2.1 不初始化或赋为非ON的值，全部视为OFF
- 2.2.2 在定义语句执行后才有效；在定义之前均视为未定义（除过在CMake命令中通过-D预定义）
- 2.2.3 已定义option选项会存储在CMakeCache.txt中。等价于缓存变量作用。
- 2.2.4 如果出现同名的变量（普通或缓存变量），则option会被忽略
- 2.2.5 CMake命令中通过-D预设同名变量，则option也会被忽略（其本质与2.2.4相同）
- 2.2.6 修改option选项值（建议通过缓存变量方式修改）
- 1 选项
CMake语法—选项（option）
1 选项
1.1 定义
| option( |
1.2 说明
- variable 选项名
- help_text 描述、解释、备注
- value 选项初始化值（除ON而外全为OFF）
cmake 编译选项管理：
在工程的根目录，编写CMakeLists.txt, 除了直接初始化函数的值外，还可以另外创建一个独立的option.txt,专门管理编译选项，语法如下：
在CMakeLists.txt中加如下语句
include option.txt
在option.txt中添加以下语句
option (USE_MYMATH
“Use tutorial provided math implementation” ON)
在编译之前，执行ccmake .就会弹出cmake GUI，进行配置所有的编译开关，配置结束后会生成一个CMakeCache.txt，配置后的编译选择保存在这个文件中。
make VERBOSE=1
2 应用注意事项
2.1 代码结构
-
learn_cmake：为根目录
-
build：为CMake配置输出目录（在此例中即生成sln解决方案的地方）
-
CMakeLists.txt：CMake脚本
-
cmake_config.bat：执行CMake配置过程的脚本（双击直接运行）
@echo off set currentDir=%~dp0 set buildDir=%currentDir% set cmakeOutputDir=%currentDir%build cmake -S %buildDir% -B %cmakeOutputDir% -G"Visual Studio 16 2019" -T v140 -A x64 pause
2.2 注意事项
2.2.1 不初始化或赋为非ON的值，全部视为OFF
-
示例代码
cmake_minimum_required(VERSION 3.18) # 设置工程名称 set(PROJECT_NAME KAIZEN) # 设置工程版本号 set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号") # 工程定义 project(${PROJECT_NAME} LANGUAGES CXX C VERSION ${PROJECT_VERSION} ) # 打印开始日志 message(STATUS "n########## BEGIN_TEST_OPTION") ## 示例1：不赋值 option(${PROJECT_NAME}_BUILD_TEST "构建测试模块") if (DEFINED ${PROJECT_NAME}_BUILD_TEST) message(STATUS "defined KAIZEN_BUILD_TEST") else() message(STATUS "not defined KAIZEN_BUILD_TEST") endif() if (${PROJECT_NAME}_BUILD_TEST) message(STATUS "KAIZEN_BUILD_TEST is ON") else() message(STATUS "KAIZEN_BUILD_TEST is OFF") endif() message(STATUS "n") ## 示例2：赋值为非ON、非OFF值 option(${PROJECT_NAME}_BUILD_EXAMPLE "构建示例模块" AAA) if (DEFINED ${PROJECT_NAME}_BUILD_EXAMPLE) message(STATUS "defined KAIZEN_BUILD_EXAMPLE") else() message(STATUS "not defined KAIZEN_BUILD_EXAMPLE") endif() if (${PROJECT_NAME}_BUILD_EXAMPLE) message(STATUS "KAIZEN_BUILD_EXAMPLE_1 is ON") else() message(STATUS "KAIZEN_BUILD_EXAMPLE_1 is OFF") endif() if (${${PROJECT_NAME}_BUILD_TYPE}) message(STATUS "KAIZEN_BUILD_EXAMPLE_2 is ON") else() message(STATUS "KAIZEN_BUILD_EXAMPLE_2 is OFF") endif() message(STATUS "n") ## 示例3：赋值为ON option(${PROJECT_NAME}_BUILD_GUI "构建视图模块" ON) if (DEFINED ${PROJECT_NAME}_BUILD_GUI) message(STATUS "defined KAIZEN_BUILD_GUI") else() message(STATUS "not defined KAIZEN_BUILD_GUI") endif() if (${PROJECT_NAME}_BUILD_GUI) message(STATUS "KAIZEN_BUILD_GUI is ON") else() message(STATUS "KAIZEN_BUILD_GUI is OFF") endif() # 打印结束日志 message(STATUS "########## END_TEST_OPTIONn") -
运行结果
-- Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763. -- The CXX compiler identification is MSVC 19.0.24245.0 -- The C compiler identification is MSVC 19.0.24245.0 -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting C compile features -- Detecting C compile features - done -- ########## BEGIN_TEST_OPTION -- defined KAIZEN_BUILD_TEST -- KAIZEN_BUILD_TEST is OFF -- -- defined KAIZEN_BUILD_EXAMPLE -- KAIZEN_BUILD_EXAMPLE_1 is OFF -- KAIZEN_BUILD_EXAMPLE_2 is OFF -- -- defined KAIZEN_BUILD_GUI -- KAIZEN_BUILD_GUI is ON -- ########## END_TEST_OPTION -- Configuring done -- Generating done -- Build files have been written to: F:/learn_cmake/build 请按任意键继续. . .
2.2.2 在定义语句执行后才有效；在定义之前均视为未定义（除过在CMake命令中通过-D预定义）
-
示例代码
cmake_minimum_required(VERSION 3.18) # 设置工程名称 set(PROJECT_NAME KAIZEN) # 设置工程版本号 set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号") # 工程定义 project(${PROJECT_NAME} LANGUAGES CXX C VERSION ${PROJECT_VERSION} ) # 打印开始日志 message(STATUS "n########## BEGIN_TEST_OPTION") ## 定义之前是看不到的 if (DEFINED ${PROJECT_NAME}_BUILD_TEST) message(STATUS "defined KAIZEN_BUILD_TEST") else() message(STATUS "not defined KAIZEN_BUILD_TEST") endif() ## 定义语句 option(${PROJECT_NAME}_BUILD_TEST "构建测试模块" ON) ## 定义后才可以看到 if (DEFINED ${PROJECT_NAME}_BUILD_TEST) message(STATUS "defined KAIZEN_BUILD_TEST") else() message(STATUS "not defined KAIZEN_BUILD_TEST") endif() ## 定义后再应用 if (${PROJECT_NAME}_BUILD_TEST) message(STATUS "KAIZEN_BUILD_TEST is ON") else() message(STATUS "KAIZEN_BUILD_TEST is OFF") endif() # 打印结束日志 message(STATUS "########## END_TEST_OPTIONn") -
运行结果
-- Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763. -- The CXX compiler identification is MSVC 19.0.24245.0 -- The C compiler identification is MSVC 19.0.24245.0 -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting C compile features -- Detecting C compile features - done -- ########## BEGIN_TEST_OPTION -- not defined KAIZEN_BUILD_TEST -- defined KAIZEN_BUILD_TEST -- KAIZEN_BUILD_TEST is ON -- ########## END_TEST_OPTION -- Configuring done -- Generating done -- Build files have been written to: F:/learn_cmake/build 请按任意键继续. . .
2.2.3 已定义option选项会存储在CMakeCache.txt中。等价于缓存变量作用。
运行2.2.1中的示例代码，然后可以查看build目录下的CMakeCache.txt文件。如下图：
2.2.4 如果出现同名的变量（普通或缓存变量），则option会被忽略
-
示例代码
cmake_minimum_required(VERSION 3.18) # 设置工程名称 set(PROJECT_NAME KAIZEN) # 设置工程版本号 set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号") # 工程定义 project(${PROJECT_NAME} LANGUAGES CXX C VERSION ${PROJECT_VERSION} ) # 打印开始日志 message(STATUS "n########## BEGIN_TEST_OPTION") ## 1.1先定义普通变量 set(${PROJECT_NAME}_BUILD_TEST "构建测试模块") if (DEFINED ${PROJECT_NAME}_BUILD_TEST) message(STATUS "defined KAIZEN_BUILD_TEST") else() message(STATUS "not defined KAIZEN_BUILD_TEST") endif() message(STATUS "KAIZEN_BUILD_TEST_1: ${${PROJECT_NAME}_BUILD_TEST}n") ## 1.2再定义同名option选项 option(${PROJECT_NAME}_BUILD_TEST "构建测试模块" ON) message(STATUS "KAIZEN_BUILD_TEST_2: ${${PROJECT_NAME}_BUILD_TEST}n") ### 2.1先定义option选项 option(${PROJECT_NAME}_BUILD_EXAMPLE "构建示例模块" OFF) if (DEFINED ${PROJECT_NAME}_BUILD_EXAMPLE) message(STATUS "defined KAIZEN_BUILD_EXAMPLE") else() message(STATUS "not defined KAIZEN_BUILD_EXAMPLE") endif() message(STATUS "KAIZEN_BUILD_EXAMPLE_1: ${KAIZEN_BUILD_EXAMPLE}") ### 2.2再定义普通同名变量 set(${PROJECT_NAME}_BUILD_EXAMPLE "构建示例模块") message(STATUS "KAIZEN_BUILD_EXAMPLE_2: ${KAIZEN_BUILD_EXAMPLE}") # 打印结束日志 message(STATUS "########## END_TEST_OPTIONn") -
运行结果
-- Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763. -- The CXX compiler identification is MSVC 19.0.24245.0 -- The C compiler identification is MSVC 19.0.24245.0 -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/amd64/cl.exe - skipped -- Detecting C compile features -- Detecting C compile features - done -- ########## BEGIN_TEST_OPTION -- defined KAIZEN_BUILD_TEST -- KAIZEN_BUILD_TEST_1: 构建测试模块 -- KAIZEN_BUILD_TEST_2: 构建测试模块 -- defined KAIZEN_BUILD_EXAMPLE -- KAIZEN_BUILD_EXAMPLE_1: OFF -- KAIZEN_BUILD_EXAMPLE_2: 构建示例模块 -- ########## END_TEST_OPTION -- Configuring done -- Generating done -- Build files have been written to: F:/learn_cmake/build 请按任意键继续. . .
2.2.5 CMake命令中通过-D预设同名变量，则option也会被忽略（其本质与2.2.4相同）
-
示例代码
cmake_minimum_required(VERSION 3.18) # 设置工程名称 set(PROJECT_NAME KAIZEN) # 设置工程版本号 set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号") # 工程定义 project(${ PROJECT_NAME } LANGUAGES CXX C VERSION ${ PROJECT_VERSION } ) # 打印开始日志 message(STATUS "n########## BEGIN_TEST_OPTION") if (DEFINED ${ PROJECT_NAME }_BUILD_EXAMPLE) message(STATUS "defined KAIZEN_BUILD_EXAMPLE") else() message(STATUS "not defined KAIZEN_BUILD_EXAMPLE") endif() ## 定义option选项 option(${ PROJECT_NAME }_BUILD_EXAMPLE "构建示例模块" OFF) message(STATUS "KAIZEN_BUILD_EXAMPLE: ${KAIZEN_BUILD_EXAMPLE}") # 打印结束日志 message(STATUS "########## END_TEST_OPTIONn") -
cmake_config.bat
@echo off set currentDir=%~dp0 set buildDir=%currentDir% set cmakeOutputDir=%currentDir%build cmake -S %buildDir% -B %cmakeOutputDir% -G"Visual Studio 16 2019" -T v140 -A x64 -DKAIZEN_BUILD_EXAMPLE=ON pause -
运行结果
--Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763. --The CXX compiler identification is MSVC 19.0.24245.0 --The C compiler identification is MSVC 19.0.24245.0 --Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler : C: / Program Files(x86) / Microsoft Visual Studio 14.0 / VC / bin / amd64 / cl.exe - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler : C: / Program Files(x86) / Microsoft Visual Studio 14.0 / VC / bin / amd64 / cl.exe - skipped -- Detecting C compile features -- Detecting C compile features - done -- ########## BEGIN_TEST_OPTION -- defined KAIZEN_BUILD_EXAMPLE -- KAIZEN_BUILD_EXAMPLE: ON -- ########## END_TEST_OPTION -- Configuring done -- Generating done -- Build files have been written to : F: / learn_cmake / build 请按任意键继续. . .
2.2.6 修改option选项值（建议通过缓存变量方式修改）
-
示例代码
cmake_minimum_required(VERSION 3.18) # 设置工程名称 set(PROJECT_NAME KAIZEN) # 设置工程版本号 set(PROJECT_VERSION "1.0.0.10" CACHE STRING "默认版本号") # 工程定义 project(${ PROJECT_NAME } LANGUAGES CXX C VERSION ${ PROJECT_VERSION } ) # 打印开始日志 message(STATUS "n########## BEGIN_TEST_OPTION") if (DEFINED ${ PROJECT_NAME }_BUILD_EXAMPLE) message(STATUS "defined KAIZEN_BUILD_EXAMPLE") else() message(STATUS "not defined KAIZEN_BUILD_EXAMPLE") endif() ## 定义option选项 option(${ PROJECT_NAME }_BUILD_EXAMPLE "构建示例模块" OFF) message(STATUS "KAIZEN_BUILD_EXAMPLE_1: ${KAIZEN_BUILD_EXAMPLE}") ## 方式一：修改option选项值（无效方式，请忽略） option(${ PROJECT_NAME }_BUILD_EXAMPLE "构建示例模块" ON) message(STATUS "KAIZEN_BUILD_EXAMPLE_2: ${KAIZEN_BUILD_EXAMPLE}") ## 方式二：通过cache变量方式修改（正确方式，力推荐） set(${ PROJECT_NAME }_BUILD_EXAMPLE ON CACHE BOOL "构建示例模块" FORCE) message(STATUS "KAIZEN_BUILD_EXAMPLE_3: ${KAIZEN_BUILD_EXAMPLE}") # 打印结束日志 message(STATUS "########## END_TEST_OPTIONn") -
运行结果
--Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.17763. --The CXX compiler identification is MSVC 19.0.24245.0 --The C compiler identification is MSVC 19.0.24245.0 --Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler : C: / Program Files(x86) / Microsoft Visual Studio 14.0 / VC / bin / amd64 / cl.exe - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler : C: / Program Files(x86) / Microsoft Visual Studio 14.0 / VC / bin / amd64 / cl.exe - skipped -- Detecting C compile features -- Detecting C compile features - done -- ########## BEGIN_TEST_OPTION -- not defined KAIZEN_BUILD_EXAMPLE -- KAIZEN_BUILD_EXAMPLE_1: OFF -- KAIZEN_BUILD_EXAMPLE_2 : OFF -- KAIZEN_BUILD_EXAMPLE_3 : ON -- ########## END_TEST_OPTION -- Configuring done -- Generating done -- Build files have been written to : F: / learn_cmake / build 请按任意键继续. . . 当然，也可以通过定义同名普通变量方式进行修改。
但是，通过普通变量方式修改后，CMakeCache.txt中的值仍然为旧值。感兴趣可自行验证。
option选项本质与缓存变量相同，即会存储在CMakeCache.txt中。因此修改其值也推荐使用缓存变量的方式，这样会直接修改CMakeCache.txt中的存储值，更彻底、更本质、更安全。
