CMake - linking to library downloaded from ExternalProject_add()

Question

I am trying to use ExternalProject_add() to download/install dependencies. It installs fine, but I can\'t figure out how to actually link the libraries after they are downlo

Answer 1

Because you're downloading the external project, you already know where everything is because you just downloaded it, so it doesn't need 'finding'.

I got it working with add_library. This is my actual code that works:

ExternalProject_Add(ForexConnectDownload
    PREFIX 3rd_party
    #--Download step--------------
    URL http://fxcodebase.com/bin/forexconnect/1.3.1/ForexConnectAPI-1.3.1-Linux-x86_64.tar.gz
    URL_HASH SHA1=7fdb90a2d45085feb8b76167cae419ad4c211d6b
    #--Configure step-------------
    CONFIGURE_COMMAND ""
    #--Build step-----------------
    BUILD_COMMAND ""
    #--Install step---------------
    UPDATE_COMMAND "" # Skip annoying updates for every build
    INSTALL_COMMAND ""
)

SET(FXCM_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/3rd_party/src/ForexConnectDownload/include)
SET(FXCM_LIB_DIR ${CMAKE_CURRENT_BINARY_DIR}/3rd_party/src/ForexConnectDownload/lib)

add_library(ForexConnect SHARED IMPORTED)
set_target_properties(ForexConnect PROPERTIES IMPORTED_LOCATION ${FXCM_LIB_DIR}/libForexConnect.so)

From there, each program that depends on it needs a add_dependencies and of course target_link_libraries. Eg:

include_directories(${FXCM_INCLUDE_DIR})
add_executable(syncDatabase syncDatabase.cpp trader/database.cpp trader/fxcm.cpp)
target_link_libraries(syncDatabase ForexConnect)
add_dependencies(syncDatabase ForexConnectDownload)

• include_directories - tells it to search for directories there
• target_link_libraries - just add your library, as you named it (not a variable)

The add_dependencies makes it wait before trying to include the dirs needed.

That does the trick for me. Works with make -j4. Get's all the dependencies right.