CMAKE: Build library and link against it

Question

I\'m trying to use cmake (on Linux with GNU make and g++) to build a project with two sub-directories: MyLib and MyApp. MyLib contains source for a static library; MyApp needs

Answer 1

1. Use "out of the source build". Make a directory used only for build and while in it, call

   cmake <path to the sources, it may be relative>

2. Either use

   link_directories(${MyProj_BINARY_DIR}/MyLib)

   or make CMakeLists.txt in each subdirectory - that would be better for project larger than very small.

3. This is a bit tricky, check out CMAKE_BUILD_TYPE in the docs (you can set it and/or "if" by it). You can also set it from command line:

   cmake -DCMAKE_BUILD_TYPE=Debug

Answer 2

Well, it is better to read this example and do exactly as suggested.

cmake_minimum_required (VERSION 2.6)
project (MyProj CXX)
add_subdirectory(MyLib)
add_subdirectory(MyApp)

Then for each subdirectory specified, CMakeLists.txt files are created

MyLib\CMakeLists.txt

file(GLOB SRC_FILES *.cpp)
add_library(MyLib ${SRC_FILES})

MyApp\CMakeLists.txt

file(GLOB SRC_FILES *.cpp)
add_executable(MyApp ${SRC_FILES})
target_link_libraries(MyApp MyLib) 

Answer 3

Do not add libraries and executables in the root Cmakelists.txt. Add these libraries and executables in Cmakelists.txt of subdirectories.

Answer 4

I've discovered the 'optimal' solution to (1)... so, thought I should post it here:

SET(CMAKE_ARCHIVE_OUTPUT_DIRECTORY MyStage)
SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY MyStage)

The thing that confused me previously is that static libraries are not considered a LIBRARY by Cmake - they're considered to be ARCHIVEs.