Multiple directories under CMake

Question

I'm currently using recursive make and autotools and am looking to migrate to CMake for a project that looks something like this:

lx/ (project root)
    src/
        lx.c (contains main method)
        conf.c
        util/
            str.c
            str.h
            etc.c
            etc.h
        server/
            server.c
            server.h
            request.c
            request.h
        js/
            js.c
            js.h
            interp.c
            interp.h
    bin/
        lx (executable)

How should I go about this?

Answer 1

If there's never any source higher than the lx/src directory, then there's no need for the lx/CMakeLists.txt file. If there is, it should look something like this:

cmake_minimum_required(VERSION 2.8 FATAL_ERROR) project(lx)  add_subdirectory(src) add_subdirectory(dir1) add_subdirectory(dir2)  # And possibly other commands dealing with things # directly in the "lx" directory 

...where the subdirectories are added in library dependency order. Libraries that depend on nothing else should be added first, and then libraries that depend on those, and so on.

lx/src/CMakeLists.txt

cmake_minimum_required(VERSION 2.8 FATAL_ERROR) project(lx_exe)  add_subdirectory(util) add_subdirectory(js) add_subdirectory(server)  set(lx_source_files conf.c lx.c) add_executable(lx ${lx_source_files})  target_link_libraries(lx server)   # also transitively gets the "js" and "util" dependencies 

lx/src/util/CMakeLists.txt

set(util_source_files   etc.c   etc.h   str.c   str.h ) add_library(util ${util_source_files}) 

lx/src/js/CMakeLists.txt

set(js_source_files   interp.c   interp.h   js.c   js.h ) add_library(js ${js_source_files})  target_link_libraries(js util) 

lx/src/server/CMakeLists.txt

set(server_source_files   request.c   request.h   server.c   server.h ) add_library(server ${server_source_files})  target_link_libraries(server js)   # also transitively gets the "util" dependency 

Then, in a command prompt:

mkdir lx/bin cd lx/bin  cmake ..   # or "cmake ../src" if the top level   # CMakeLists.txt is in lx/src  make 

By default, the lx executable will end up in the "lx/bin/src" directory using this exact layout. You can control what directory it ends up in by using the RUNTIME_OUTPUT_DIRECTORY target property and the set_property command.

http://www.cmake.org/cmake/help/cmake-2-8-docs.html#prop_tgt:RUNTIME_OUTPUT_DIRECTORY

http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:set_property

Refer to target_link_libraries libs either by CMake target name, if the lib is built as a CMake target via add_library, or by full path to the library file otherwise.

See also, the output of "cmake --help-command target_link_libraries", or any other cmake command, and the full online documentation for cmake commands found here:

http://www.cmake.org/cmake/help/cmake-2-8-docs.html#section_Commands

http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:target_link_libraries

Answer 2

Steinberg VST3 library has a reusable method which recursively loops through subdirectories and adds them if they include a CMakeLists.txt file:

# add every sub directory of the current source dir if it contains a CMakeLists.txt function(smtg_add_subdirectories)     file(GLOB subDirectories RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} *)     foreach(dir ${subDirectories})         if(IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/${dir}")             if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/${dir}/CMakeLists.txt")                 add_subdirectory(${dir})             endif()         endif()     endforeach(dir) endfunction() 

https://github.com/steinbergmedia/vst3_cmake/blob/master/modules/SMTG_AddSubDirectories.cmake