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Adding multiple executables in CMake

My code in a C++ project is organised as follows

  • I have several .cpp and .h files which contains my classes
  • I have several .cxx files which have to be compiled against the .cpp files and some external libraries.

Now, each of the .cxx files have a main() method, so I need to add a different executable for each of these files having the same name as the file.

Also, these .cxx files might not get linked to the same external libraries.

I want to write this build in CMake, in which I am kind of a newbie, how do I go about this?

Solution

  • My suggestion is to tackle this in two phases:

    1. Build a library from the .cpp and .h files, using add_library
    2. Iterate through all your .cxx files and create an executable from each, using add_executable and foreach

    Build the library

    This could be something as simple as

    file( GLOB LIB_SOURCES lib/*.cpp )
file( GLOB LIB_HEADERS lib/*.h )
add_library( YourLib ${LIB_SOURCES} ${LIB_HEADERS} )

    Build all the executables

    Simply loop over all the .cpp files and create separate executables.

    # If necessary, use the RELATIVE flag, otherwise each source file may be listed 
# with full pathname. RELATIVE may makes it easier to extract an executable name
# automatically.
# file( GLOB APP_SOURCES RELATIVE app/*.cxx )
file( GLOB APP_SOURCES app/*.cxx )
foreach( testsourcefile ${APP_SOURCES} )
    # Cut off the file extension and directory path
    get_filename_component( testname ${testsourcefile} NAME_WE )
    add_executable( ${testname} ${testsourcefile} )
    # Make sure YourLib is linked to each app
    target_link_libraries( ${testname} YourLib )
endforeach( testsourcefile ${APP_SOURCES} )

    Some warnings:

    • file( GLOB ) is usually not recommended, because CMake will not automatically rebuild if a new file is added. I used it here, because I do not know your sourcefiles.
    • In some situations, source-files may be found with a full pathname. If necessary, use the RELATIVE flag for file(GLOB ...).
    • Manually setting the source-files requires a change to CMakeLists.txt, which triggers a rebuild. See this question for the (dis-)advantages of globbing.

    Concerning "general" CMake info, I advise you to read some of the broad "CMake Overview" questions already asked here on stackoverflow. E.g.: