CMake dependency management

We employ CPM, a CMake dependency management solution, to integrate third-party dependencies.

Dependencies are downloaded at configure-time into the build directory. Dependencies get build in the build directory inside the _deps-subdirectory.

To speed things up you can specify a cache directory for the downloads by setting CPM_SOURCE_CACHE either as an environment or CMake variable:

# Can be placed in .bashrc or .bash_profile:
export CPM_SOURCE_CACHE=$HOME/.cache/CPM
# OR
cmake ... -DCPM_SOURCE_CACHE=$HOME/.cache/CPM

Some dependencies (those which are added with CPMFindPackage()) are first searched to be locally installed on the system with a fallback to CPM if not found. You can disable the search for local packages with CPM_DOWNLOAD_ALL.

All dependencies integrated with CPM internally become part of the CMake configuration. Some dependencies are not compatible with this approach (e.g. VTK and PETSc) and are therefore integrated as CMake external projects. Per default they are automatically downloaded, configured and build inside the build directory during CMake configuration. If CPM_SOURCE_CACHE is set the downloads and builds are cached in the specified directory as well under $CPM_SOURCE_CACHE/_ext. To remove the cache simply delete the cache folder and configure a new build.

Further information

• CPM on GitHub
• Blog post: An Awesome Dependency Manager for C++ with CMake
• Blog post: CMake and the Future of C++ Package Management