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I'm trying to put together a CMake project where I have different packages that I need to build. This is my desired structure:

package1 src file.cpp test file_test.cpp package2 src file2.cpp test file2_test.cpp CMakeLists.txt main.cpp // this will be removed later

This is my current CMakeLists.txt file:

cmake_minimum_required(VERSION 3.10) # set the project name project(cppApp) # specify the C++ standard set(CMAKE_CXX_STANDARD 11) set(CMAKE_CXX_STANDARD_REQUIRED True) include_directories(${PROJECT_SOURCE_DIR}) # add the executable add_executable(cppApp main.cpp ./package1/src/file.cpp ./package2/src/file2.cpp)

So the question is firstly, is a library considered a package in CMake? This question comes from someone who have done a lot of Java where I would typically call that a package and not a library. But does it in CMake?

Also, how do I in CMake include all files in the "packages" to be built instead of hard coding in the files as an executable? If I create many .cpp/.h files I want to automate this as much as possible.

I have seen that some other projects use a CMakeLists.txt file inside each "package", is this ideal? And is this good practice?

If you have a better suggestion according to some standard I should use to structure my project I would like to know a good one as well.

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  • Can you please elaborate about the "package" term? It's completely unclear what is considered being one. Commented Apr 9, 2022 at 9:59
  • Package in Java is not a library, it's a way to organize classes into namespaces. They could be libraries or part of your own project. In C++ you use namespaces for the exact same purpose Commented Apr 9, 2022 at 10:01
  • Yes that I understand. That's why I wanted some clarification if in C++/CMake what the definition is and how I should think according to my structure and how to build it. CMake have something called add_library(lib) and is those kinds of directories considered a library? Can something nudge me in the right direction or show some kind of example how that differs and how to add that to a CMake file for it to build? Commented Apr 9, 2022 at 10:06
  • A package is a package, a library is a library; both aren't synonyms in C++ (and therefore CMake). A package in cmake terms has more in common with e.g. apt packages: One package may contain an arbitary number of executables, libraries, header files, ect. Note that this does indeed mean a header only library could be considered a package. As for creating a package in CMake: that would be done using cmake --install ..., cpack which work based on the install cmake command among other things but to me it seems like that's not what you're hoping to achieve right now. Commented Apr 9, 2022 at 11:33
  • you can use file(GLOB SRC_FILES dir/*.cpp) to automate listing of source files but there are performance issues, partially solved by CONFIGURE_DEPENDS keyword, not mentioning that you may list files which you do not actually want as part of Commented Apr 9, 2022 at 12:19

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So the question is firstly, is a library considered a package in CMake? This question comes from someone who have done a lot of Java where I would typically call that a package and not a library. But does it in CMake?

Your definition of package in Java is not quite accurate. Package is just a mean to organize classes in Java in namespace manner. It could be classes of a separate library, but nothing prevents you from using different packages within the same project. It has nothing to do with CMake packages, where each package is actually a whole separate project.

I have seen that some other projects use a CMakeLists.txt file inside each "package", is this ideal? And is this good practice?

CMakeLists.txt files in subdirectories merely define new subset of rules for those directories. In order to make your CMake project respect those rules, you add such directory with add_subdirectory. It's not neccessarily a separate library, you can make subset of rules for parts of a single project, and it's usually a good idea to do that if some files are really that different.

CMake have something called add_library(lib) and is those kinds of directories considered a library?

add_library creates so-called CMake target, just like add_executable. The targets can be linked with each other with use of target_link_libraries, and that will indeed be considered a library in terms of C++.

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