Keeping file hierarchy across subdirectories in CMake

Question

Till date I still do not really understand what the \'best practice\' is for doing this for a CMake project with many subdirectories.

Say I have a project hierarchy

Answer 1

There are 3 ways I have used before. I normally prefer the 1st way, but have already used all 3 depending on the use case:

1. You directly name the sources in your root CMakeLists.txt file

set(
    SUBD1_SOURCES
    "SubD1/SubSubD1/Source2.cpp"
    "SubD1/Source.cpp"
)

set(
    SUBD2_SOURCES
    "SubD2/Source3.cpp"
)

add_executable(myProg ${SUBD1_SOURCES} ${SUBD2_SOURCES})

2. You use OBJECT intermediate libraries to collect/group your sources

SubD1/SubSubD1/CMakeLists.txt:

add_library(SubSubD1Objs OBJECT Source2.cpp)

SubD1/CMakeLists.txt:

add_subdirectory(SubSubD1)
add_library(SubD1Objs OBJECT Source.cpp)

CMakeLists.txt:

add_executable(myProg $ $)

3. You write your own function() to collect the data (and do the prefixing)

CMakeLists.txt:

function(my_collect_sources)
    foreach(_source IN ITEMS ${ARGN})
        if (IS_ABSOLUTE "${_source}")
            set(source_abs "${_source}")
        else()
            get_filename_component(_source_abs "${_source}" ABSOLUTE)
        endif()
        set_property(GLOBAL APPEND PROPERTY GlobalSourceList "${_source_abs}")
    endforeach()
endfunction(my_collect_sources)

add_subdirectory(SubD1)
#add_subdirectory(SubD2)

get_property(MY_SOURCES GLOBAL PROPERTY GlobalSourceList)
add_executable(myProg ${MY_SOURCES})

SubD1/CMakeLists.txt:

add_subdirectory(SubSubD1)
my_collect_sources(Source.cpp)

SubD1/SubSubD1/CMakeLists.txt:

my_collect_sources(Source2.cpp)