Include rather than find_package makes eventual shared reuse harder

[steve-downey]

exemplar/CMakeLists.txt

Lines 27 to 28 in ddfe5ba

	# for find of beman-install-library
	include(infra/cmake/beman-install-library-config.cmake)

Making this an include with a path, rather than a find_package and setting the module path, means that we can't easily re-use the infra package once it stabilizes. It must be in tree and infra merged in for a package to get any shared benefits.

Having the infra directory in tree is a tradeoff to allow looser coupling without the problems of submodules, and for a project to use and propose changes to the infra facilities. But scaling the reuse means using infra by a package, not by vendoring.

[ClausKlein]

find_package() is not needed and the overkill for that.

only include(beman-install-library-config) if the toolchain appends the right CMAKE_MODULE_PATH which is needed for dependency provider too.

[ednolan]

A few thoughts on this:

• While we have a path forward to packaging the parts of infra that are CMake modules, like beman-install-library-config.cmake, and I think we should do so, we have no path forward to packaging the CMake toolchain files that infra includes, because of the chicken-egg problem. Probably we should split those up into separate repositories.
• Until we actually have a package for the CMake modules, I don't see a lot of benefit in prematurely switching to find_package. We can just change over to find_package when we have one.
• I would also like to eliminate the need to set CMAKE_MODULE_PATH.