[cmake-developers] Should configuration package files define module package variables?

[Robert Dailey]

So I've been studying the find_package[1] and "creating packages"[2]
documentation, as well as the CMakePackageConfigHelpers[3] page.

Based on the current offerings of configuration packages, I do not
understand the need for the relocatable config.cmake file when all it
really contains is:

include(${CMAKE_CURRENT_LIST_DIR}/foo-config.cmake)

However, what I'm wondering is even though the import targets should
contain all information about include directories, libraries, etc,
should I still define the typical Foo_INCLUDE_DIRS, Foo_LIBRARIES
variables? Example of what foo-config.cmake would be like:

include(${CMAKE_CURRENT_LIST_DIR}/foo-config.cmake)
set( Foo_INCLUDE_DIRS "... path here...." )
set( Foo_LIBRARIES "List of libraries here..." )


Is this necessary? Honestly the learning curve for creating packages
for find_package is very steep. I did not see any general advice on
this kind of stuff. It seems like Module packages are being deprecated
in favor of Config packages, because it puts the responsibility of
maintaining find package logic on the upstream maintainer (config
package) instead of on CMake (module packages it ships with).

Thanks in advance for any help.