What is the location to install .cmake extension files in Ubuntu?

Question

I am working on various projects, some of which offer a .cmake extension which I want to install whenever the development package of the project is installed on your Ubuntu system.

The modules of cmake 2.8 are saved under

/usr/share/cmake-2.8/Modules/...

and I thought that was were I would want to install my own extensions (knowing that it would break once we go to cmake-3.0).

However, there seems to be another location where packages install their own extensions:

/usr/share/cmake/<project-name>/...

Is there a place where I could find documentation about this? So far my searches on Google have not pointed me in the right direction...

I have found the following answer, but that seems to be specific to cmake and not Ubuntu:

CMake: Where to install FooBarConfig.cmake and FooBarConfigVersion.cmake?

Answer 1

You can use the CMake package configuration mechanism, which you mentioned in your question.

Imaging you have the following CMake files:

SomeProjectConfig.cmake
SomeProjectConfigVersion.cmake
SomeProjectExtensions.cmake

The SomeProjectConfig.cmake and SomeProjectConfigVersion.cmake can be generated by CMakePackageConfigHelpers module.

You can install them into /usr/share/cmake/SomeProject/ folder, for example. For full list of default paths used by CMake see find_package documentation.

In your SomeProjectConfig.cmake you can include the SomeProjectExtensions.cmake file or expand CMAKE_MODULE_PATH variable to let user include the CMake script:

# SomeProjectConfig.cmake
list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR})
set(SOME_PROJECT_SOME_VAR "...")
function(some_project_func)
    ...
endfunction()

Now your users might use your CMake scripts via find_package:

# User CMakeLists.txt
find_package(SomeProject REQUIRED)
message(STATUS "SOME_PROJECT_SOME_VAR = ${SOME_PROJECT_SOME_VAR}")
some_project_func()
include(SomeProjectExtensions)