为新手创建CMakeFiles.txt文件

Question

我有一个具有以下结构的项目

  /cmake_modules/
    FindSFML.cmake
  /includes/
    car.hpp
    motor.hpp
    tires.hpp
  /sources/
    car.cpp
    motor.cpp
    tires.cpp    
  /main.cpp
  /main.hpp

我有以下CMakeFiles.txt文件：

cmake_minimum_required(VERSION 2.8)

project (MYGAME)
set (MYGAME_VERSION_MAJOR 1)
set (MYGAME_VERSION_MINOR 0)

set (EXECUTABLE_NAME "mygame")

include_directories ("${MYGAME_BINARY_DIR}")
include_directories ("${MYGAME_BINARY_DIR}/includes")
link_directories ("${MYGAME_BINARY_DIR}/sources")

add_executable(${EXECUTABLE_NAME} main.cpp)

set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake_modules" ${CMAKE_MODULE_PATH})
find_package(SFML 2.0 REQUIRED system window graphics network audio)

target_link_libraries(${EXECUTABLE_NAME} ${SFML_LIBRARIES})

---

当我尝试执行时make，得到以下信息：

[100%] Building CXX object CMakeFiles/mygame.dir/main.cpp.o
Linking CXX executable mygame
CMakeFiles/mygame.dir/main.cpp.o: In function `main':
main.cpp:(.text+0x11): undefined reference to `mynamespace::Car::Instance()'
main.cpp:(.text+0x21): undefined reference to `mynamespace::Car::start()'
collect2: error: ld returned 1 exit status
make[2]: *** [mygame] Error 1
make[1]: *** [CMakeFiles/mygame.dir/all] Error 2
make: *** [all] Error 2

我如何解决它？

Answer 1

您需要以某种方式将其余资源（car.cpp，motor.cpp和tires.cpp）包括在构建中。

您可以将它们与main.cpp一起直接添加到可执行文件中：

set(MySources sources/car.cpp sources/motor.cpp sources/tires.cpp main.cpp)
add_executable(${EXECUTABLE_NAME} ${MySources})

或者您可以将它们放入库中并链接：

set(MyLibSources sources/car.cpp sources/motor.cpp sources/tires.cpp)
add_library(MyLib ${MyLibSources})
add_executable(${EXECUTABLE_NAME} main.cpp)
...
target_link_libraries(${EXECUTABLE_NAME} MyLib ${SFML_LIBRARIES})

还有两点需要注意：

link_directories如果可能的话，应避免使用它（其自身的文档会妨碍其使用），并且将标头包含在通过add_executable或添加的文件列表中通常很有帮助，add_library因为这些标头随后会显示在MS Visual Studio等IDE中。