david.rabine

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====== Layout ======

  * [[https://cliutils.gitlab.io/modern-cmake/chapters/basics/structure.html]] <- good example layout

===== Example Structure Build =====

==== Core Hello World ====

Sample structure layout
  * project
    * bin
      * utils
      * tests
        * hello_world
    * build
    * include
    * lib

  - make a folder for your project and here is the top layer CMakeLists.txt file <code>
project(lvis24)
cmake_minimum_required(VERSION 3.0)

add_subdirectory( bin )
</code>
  - create a .gitignore to exclude **build** folder so repos/project/.gitignore should contain this <code>
# ignore the build directory
build/*
</code>
  - CMakeLists.txt in bin <code>
add_subdirectory( tests )
</code>
  - CMakeLists.txt in tests <code>
add_subdirectory( hello_world )
</code>

Now you can compile it all by
  - going to ~/project/build
  - cmake ..
  - build

==== Adding Library ====

  - Add a **lib** directory and now our file looks like this <code>
project(lvis24)
cmake_minimum_required(VERSION 3.0)

add_subdirectory(bin)
add_subdirectory(lib)
</code>
  - in **lib** just add the sub directory also <code>
# cat CMakeLists.txt 
add_subdirectory( hello_lib )
</code>
  - in the actual library directory we add a few things <code>
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)
</code>
  - back in hello world binary now we need to add this library for compile time <code>
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)
</code>

Does this work? (spoiler alert... yep!) <code>
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!


</code>

==== Example With Lib ====

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

  * {{ :code:work:generic:cmake:lvis24_cmake_source_tree_example.tar.gz |}} very basic hello world and hello world library cmake skeleton example.