# CMake usage¶

This is a brief guide to our CMake infrastructure which is managed via Autocmake

Warning

The minimum required CMake version is 2.8.10

## Adding new source subdirectories and/or files¶

Developers HAVE TO manually list the sources in a given subdirectory of the main source directory src/. In our previous infrastructure this was not necessary, but the developers needed to trigger CMake to regenerate the Makefiles manually.

### New subdirectory¶

First of all, you will have to let CMake know that a new source-containing subdirectory has been added to the source tree. Due to the hierarchical approach CMake is based upon you will need to modify the CMakeLists.txt in the src directory and create a new one in your new subdirectory. For the first step:

1. if your new subdirectory contains header files, add a line like the following to the CMakeLists.txt file contained in the src directory:

${CMAKE_CURRENT_LIST_DIR}/subdir_name to the command setting the list of directories containing headers. This sets up the list of directories where CMake will look for headers with definitions of classes and functions. If your directory contains Fortran code you can skip this step; 2. add a line like the following to the CMakeLists.txt file contained in the src directory: add_subdirectory(subdir_name) This will tell CMake to go look inside subdir_name for a CMakeLists.txt containing more sets of instructions. It is preferable to add these new lines in alphabetic order Inside your new subdirectory you will need to add a CMakeLists.txt file containing the set of instructions to build your cutting edge code. This is the second step. Run the make_cmake_files.py Python script in the src/ directory: python make_cmake_files.py --libname=cavity --lang=CXX to generate a template CMakeLists.txt.try file: # List of headers list(APPEND headers_list Cavity.hpp ICavity.hpp Element.hpp GePolCavity.hpp RegisterCavityToFactory.hpp RestartCavity.hpp) # List of sources list(APPEND sources_list ICavity.cpp Element.cpp GePolCavity.cpp RestartCavity.cpp) add_library(cavity OBJECT${sources_list} ${headers_list}) set_target_properties(cavity PROPERTIES POSITION_INDEPENDENT_CODE 1 ) set_property(GLOBAL APPEND PROPERTY PCMSolver_HEADER_DIRS${CMAKE_CURRENT_LIST_DIR})
# Sets install directory for all the headers in the list
foreach(_header ${headers_list}) install(FILES${_header} DESTINATION include/cavity)
endforeach()

The template might need additional editing. Each source subdirectory is the lowest possible in the CMake hierarchy and it contains set of instructions for:

1. exporting a list of header files (.h or .hpp) to the upper level in the hierarchy, possibly excluding some of them
2. define install targets for the files in this subdirectory.

All the source files are compiled into the unique static library libpcm.a and unique dynamic library libpcm.so. This library is the one the host QM program need to link.

### Searching for libraries¶

In general, the use of the find_package macro is to be preferred, as it is standardized and ensured to work on any platform. Use of find_package requires that the package/library you want to use has already a module inside the CMake distribution. If that’s not the case, you should never use the following construct for third-party libraries: