CMake : how to link a library WITHOUT automatic search function FIND_PACKAGE?

Question

I wonder how to find/link a library without any FIND_PACKAGE.

Assume that we have a \"personal\" library called testlib :

/perso/testlib/include/test         


        

Answer 1

You can use target_link_libraries(myexecutable mylib) to link to the library "mylib". The compiler will use its default way to find the specified library (e.g. it will look for libmylib.a on Linux). The compiler will only look in the link_directories(directory1 directory2 ...), so you could try that command to add the required directories to the search path.

When "mylib" is also compiled with CMake this will be recognized and everything should work automatically.

When you want the user to specify a directory you can use a cached CMake variable. set(MYPATH "NOT-DEFINED" CACHE PATH "docstring").

For more complex stuff it is very advisable to write a CMake find module that can be used with find_package. I suggest you take a look at the FindALSA.cmake which can be used as a good starting point.

The interesting part is at the end:

if(ALSA_FOUND)
  set( ALSA_LIBRARIES ${ALSA_LIBRARY} )
  set( ALSA_INCLUDE_DIRS ${ALSA_INCLUDE_DIR} )
endif()

mark_as_advanced(ALSA_INCLUDE_DIR ALSA_LIBRARY)

The ALSA_LIBRARY and ALSA_INCLUDE_DIR variables are user configurable and stored in the cache, while ALSA_LIBRARIES and ALSA_INCLUDE_DIRS as well as ALSA_FOUND get computed and are the ones that the user of the find module is supposed to use.

Typically one would use the find module like this:

find_package(ALSA REQUIRED)
include_directories(${ALSA_INCLUDE_DIRS})
target_link_libraries(myexe ${ALSA_LIBRARIES})

I'm sure you can adapt this for your personal library.