Layout

• https://cliutils.gitlab.io/modern-cmake/chapters/basics/structure.html ← good example layout

Sample structure layout

• project
  • bin
    • utils
    • tests
      • hello_world
  • build
  • include
  • lib

1. make a folder for your project and here is the top layer CMakeLists.txt file

   project(lvis24)
   cmake_minimum_required(VERSION 3.0)
   
   add_subdirectory( bin )

2. create a .gitignore to exclude build folder so repos/project/.gitignore should contain this

   # ignore the build directory
   build/*

3. CMakeLists.txt in bin

   add_subdirectory( tests )

4. CMakeLists.txt in tests

   add_subdirectory( hello_world )

Now you can compile it all by

1. going to ~/project/build
2. cmake ..
3. build

1. Add a lib directory and now our file looks like this

   project(lvis24)
   cmake_minimum_required(VERSION 3.0)
   
   add_subdirectory(bin)
   add_subdirectory(lib)

2. in lib just add the sub directory also

   # cat CMakeLists.txt 
   add_subdirectory( hello_lib )

3. in the actual library directory we add a few things

   project( hello_world_lib )
   
   add_library(${PROJECT_NAME} hello_world_lib.cpp hello_world_lib.h)
   
   # -shared creates the shared library
   set_target_properties(${PROJECT_NAME} PROPERTIES COMPILE_FLAGS "-O2 -Wall -shared")
   
   # if you wanted to add other libs
   # target_link_libraries(${PROJECT_NAME} crypto ssl z)

4. back in hello world binary now we need to add this library for compile time

   project(hello_world)
   cmake_minimum_required(VERSION 3.0)
   
   add_executable(${PROJECT_NAME} main.cpp)
   
   target_link_libraries(${PROJECT_NAME} hello_world_lib)
   
   include_directories(../../../lib/hello_lib)
   link_directories(../../../lib/hello_lib)

Does this work? (spoiler alert… yep!)

lvis@lvis-dell-xps:~/repos/lvis24/build$ cmake ..
-- The C compiler identification is GNU 9.4.0
-- The CXX compiler identification is GNU 9.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/lvis/repos/lvis24/build
lvis@lvis-dell-xps:~/repos/lvis24/build$ make
Scanning dependencies of target hello_world_lib
[ 25%] Building CXX object lib/hello_lib/CMakeFiles/hello_world_lib.dir/hello_world_lib.cpp.o
[ 50%] Linking CXX static library libhello_world_lib.a
[ 50%] Built target hello_world_lib
Scanning dependencies of target hello_world
[ 75%] Building CXX object bin/tests/hello_world/CMakeFiles/hello_world.dir/main.cpp.o
[100%] Linking CXX executable hello_world
[100%] Built target hello_world

lvis@lvis-dell-xps:~/repos/lvis24/build$ ./bin/tests/hello_world/hello_world 
Hello World

Hello from the library that you included!

NOTE: This source also has a skeleton of a class so you can see how to create and call your own class. 

• lvis24_cmake_source_tree_example.tar.gz very basic hello world and hello world library cmake skeleton example.