Manage native (C++) build dependencies

[rainman110]

What are the best practices, to install and use non-python dependencies with skbuild, in particular with cmake?

Is there any good example, that requires e.g. the boost libraries?

Ideally, I'd like to combine

• skbuild for the build and packaging process and
• conan to install dependencies

Is it possible to call conan install automatically by setup.py from within cmake's build directory?

[zouhairm]

@rainman110 - I'm curious how you've ended up handling this?

[rainman110]

I did not find a "best" solution unfortunately. My workaround is to manually set the "CMAKE_PREFIX_PATH" environment variable to all external dependencies first and then build the project (via scikit build).

Another workaround is to integrate the dependencies as subprojects / submodules and build everything together.

[yssource]

I'm also curious about how to make scikit-build work with conan package manager?

[zouhairm]

with the help of some cmake gurus, I ended up implementing this by relying on dependency providers. See details below:

• added a "package provider" file called conan_pkg_provide_dependency.cmake.j2
  (note, this is a jinja template as it was part of some more complicated code, but the {{ }} should be obvious

set(CONAN_PKG_PROVIDER_INSTALL_DIR ${CMAKE_BINARY_DIR}/conan_packages
  CACHE PATH "The directory this provider installs packages to"
)

macro(conan_pkg_provide_dependency method cmake_package)
  if(${cmake_package} MATCHES "{{ target_name }}")
      execute_process(
        COMMAND conan install {{ target_conan_name_version_user_channel }} --build=missing -g deploy -if ${CONAN_PKG_PROVIDER_INSTALL_DIR}
        COMMAND_ERROR_IS_FATAL ANY
      )
      find_package(${cmake_package} PATHS ${CONAN_PKG_PROVIDER_INSTALL_DIR}/{{ target_conan_name }} NO_DEFAULT_CMAKE_PATH BYPASS_PROVIDER)
  endif()
endmacro()

cmake_language(
  SET_DEPENDENCY_PROVIDER conan_pkg_provide_dependency
  SUPPORTED_METHODS FIND_PACKAGE
)

See https://cmake.org/cmake/help/latest/guide/using-dependencies/index.html

• in my CMakeLists.txt I added:

find_package({{ target_name }} REQUIRED)

which will end up using the package provider defined above since the target_name would match

• finally, in my setup() in the setup.py, I passed to cmake the following args:

cmake_args=[f'-DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={Path(__file__).parent.absolute()}/conan_pkg_provide_dependency.cmake']

See https://cmake.org/cmake/help/latest/variable/CMAKE_PROJECT_TOP_LEVEL_INCLUDES.html

[rainman110]

That looks indeed like a working solution! Thanks for sharing this! 🙏 I am going to check this out.