CMake：为目标源设置目录

Question

I have a C++ project where all implementation source files (*.cpp) reside in a src directory within the project directory. Some of the files are in further subdirectories. Let's say there are 50 files in src/foo/ . I need to list these files as part of the add_library and/or the target_sources function.

Now, everywhere one looks, adding all files from a directory automtically is discouraged, which is fine with me. So I am going to list all the files manually; but repeating the common prefix src/foo/ 50 times seems really silly and is annoying.

Inthe documentation for target_sources it says

Relative source file paths are interpreted as being relative to the current source directory (ie CMAKE_CURRENT_SOURCE_DIR).

So I've added set(CMAKE_CURRENT_SOURCE_DIR "src/foo/") before the call to target_source but it didn't work. (I get a "Cannot find source file" error.)

So what is the correct way to achieve what I want if it is even possible?

NB: The (public) header files (*.hpp) of the project are in an include directory (outside of src ). This is nicely configured (without having to list the individual files) with the target_include_directories function.

Answer 1

but repeating the common prefix src/foo/ 50 times

Just prepend the prefix to the sources.

set(target_sources
    source1.c
    source2.c
)
list(TRANSFORM target_sources PREPEND "src/foo/")

Answer 2

Setting CMAKE_CURRENT_SOURCE_DIR as a relative variable to the old CMAKE_CURRENT_SOURCE_DIR is not going to work. If it's set to a value, then it's fair to assume that removing that value and using a custom one will be wrong because you are missing what it was set to before.

You might want to set it as an absolute path, or use set(CMAKE_CURRENT_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/src/foo/") , or do as lots of other people and copy paste the prefix all the time. That's the standard practice (which is also one of the reason I still use GLOB, because I'm lazy), following up on explicit is better than implicit (which is the point of not using GLOB ).

Answer 3

You can also use add_subdirectory(src/foo) and a CMakeLists.txt in src/foo in which you only have to put

target_sources( <your target> PRIVATE|PUBLIC|INTERFACE
  your
  list
  of
  sources
)

I think that would be rather elegant.

Answer 4

I would have suggested (if you have bash or some similar shell)

function prepend() { while read line; do echo "${1}${line}"; done; }
ls *.cc *hh | sort | prepend  "\${CMAKE_CURRENT_SOURCE_DIR}/"

then copy and paste :)