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添加一个option! 添加一个option!
option#xff0c;正如其意#xff0c;就是选项的意思。我们这里需要演示一下option的做法。
option对于大型的工程必然是非常常见的#xff1a;一些模块会被要求编译#xff0c;另一些客户不准备需要这些模块。option就是将这种需…目录
添加一个option! 添加一个option!
option正如其意就是选项的意思。我们这里需要演示一下option的做法。
option对于大型的工程必然是非常常见的一些模块会被要求编译另一些客户不准备需要这些模块。option就是将这种需求组织起来让脚本构建者有了清晰的逻辑组成的抓手。
举个最最简单的例子。我们打算写一个模块这个模块其实就是根据用户静态的选择打印不同的话 impl.c void implA();
void implB();
void impl()
{
#ifdef USE_SPECIAL_IMPLimplB();
#elseimplA();
#endif
} impl(A/B).c // implA.c
#include stdio.h
void implA()
{printf(The Implement function is using Implements A);
}
// implB.c
#include stdio.h
void implB()
{printf(The Implement function is using Implements B);printf(\n which is surprised :));
}
他们都在optional_implements文件夹中
➜ tree -L 2
.
├── build
| ├─ ... # Ommited
├── CMakeLists.txt
├── Config.h.in
├── main.c
├── MathLibs
│ ├── CMakeLists.txt
│ ├── mathLibs.c
│ └── mathLibs.h
└── optional_implements├── implA.c├── implB.c└── impl.c
下面就是在cmake中体现出来了,我们使用的就是option这个命令
option(USE_SPECIAL_IMPL the special implements of impl function ON)
option这个命令的格式非常简单就是目标控制变量 描述 默认定义。这里的ON表达是开启的意思。OFF就是关闭:
cmake .. -DUSE_SPECIAL_IMPLOFF
cmake当中就是就是采用D 控制变量名称ON/OFF来决定的。
更好的办法是使用cmake-gui来进行可视化的构建 我们继续实现这个根据option来决定编译行为不一致的实现。很简单我们只需要控制
if (USE_SPECIAL_IMPL)set(CharliesDemoSrc ${CharliesDemoSrc} optional_implements/implB.c)
else()set(CharliesDemoSrc ${CharliesDemoSrc} optional_implements/implA.c)
endif()
add_executable(CharliesDemo ${CharliesDemoSrc})
if (USE_SPECIAL_IMPL)target_compile_definitions(CharliesDemo PRIVATE USE_SPECIAL_IMPL)
endif() 下面给出现在CMakeLists.txt脚本的全貌
cmake_minimum_required(VERSION 3.30)
project(CharliesDemoVERSION 1.0)
set(CharlieConstVar 1)
set(CharlieConstDouble 1.1)
configure_file(Config.h.in Config.h)
add_subdirectory(MathLibs)
set(CharliesDemoSrc main.c optional_implements/impl.c)
option(USE_SPECIAL_IMPL the special implements of impl function ON)
if (USE_SPECIAL_IMPL)set(CharliesDemoSrc ${CharliesDemoSrc} optional_implements/implB.c)
else()set(CharliesDemoSrc ${CharliesDemoSrc} optional_implements/implA.c)
endif()
add_executable(CharliesDemo ${CharliesDemoSrc})
if (USE_SPECIAL_IMPL)target_compile_definitions(CharliesDemo PRIVATE USE_SPECIAL_IMPL)
endif()
target_include_directories( CharliesDemo PUBLIC ${PROJECT_BINARY_DIR}${PROJECT_SOURCE_DIR}/MathLibs)
target_link_libraries(CharliesDemo PUBLIC MathLib)
看官自行尝试cmake的使用
➜ cd build cmake .. -DUSE_SPECIAL_IMPLOFF make
-- Configuring done (0.0s)
-- Generating done (0.0s)
-- Build files have been written to: /home/Charliechen/Works/cmake_learning/build
[ 16%] Building C object MathLibs/CMakeFiles/MathLib.dir/mathLibs.c.o
[ 33%] Linking C static library libMathLib.a
[ 33%] Built target MathLib
[ 50%] Building C object CMakeFiles/CharliesDemo.dir/main.c.o
[ 66%] Building C object CMakeFiles/CharliesDemo.dir/optional_implements/impl.c.o
[ 83%] Building C object CMakeFiles/CharliesDemo.dir/optional_implements/implA.c.o
[100%] Linking C executable CharliesDemo
[100%] Built target CharliesDemo
➜ ./CharliesDemo
VERISON_MAJOR: 11 2 3The Implement function is using Implements A⏎ ➜ cd build cmake .. -DUSE_SPECIAL_IMPLON make
-- Configuring done (0.0s)
-- Generating done (0.0s)
-- Build files have been written to: /home/Charliechen/Works/cmake_learning/build
[ 33%] Built target MathLib
[ 50%] Building C object CMakeFiles/CharliesDemo.dir/main.c.o
[ 66%] Building C object CMakeFiles/CharliesDemo.dir/optional_implements/impl.c.o
[ 83%] Building C object CMakeFiles/CharliesDemo.dir/optional_implements/implB.c.o
[100%] Linking C executable CharliesDemo
[100%] Built target CharliesDemo
VERISON_MAJOR: 11 2 3The Implement function is using Implements Bwhich is surprised :)⏎
