[CMake] about the required project label...

[J Decker]

I have a small cmake script I include at start of several projects.  I
define some things like where includes and libraries are for the
common libraries. This has worked well for the few extensions that I
did, because their root cmakelists.txt had no project.  Some things
like CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT and
CMAKE_COMPILER_IS_GNUCC *are set* as valid if you have a
cmakelists.txt with no projects, and only add_subdirectory()s.  They
are not set if you reference them before you define an initial
project.

So it's my inclination to define common functions and variables before
using them...

------------
cmake_minimum_required(VERSION 2.8)

# declare common global features
GET_FILENAME_COMPONENT(common_library_root
"[HKEY_LOCAL_MACHINE\\SOFTWARE\\Manufacturer\\Common
Library;Install_Dir]" ABSOLUTE CACHE)
include( ${common_library_root}/CMakeDefs )

PROJECT( my_new_project )

-----------

So I know know that won't work, and in the case of the cmakelists.txt
without a project, that shouldn't be done; Can maybe a warning (error)
be made that there is no PROJECT() ?

= = =

There are two ways I can work around this. (something I read recently
that I shouldn't do...)
    1) define a PROJECT( Unused_project_name ) in CMakeDefs referenced
earlier.
        a) This works 50% of the time... becuase since there are other
cmake users out there that know you shouldn't do anything before a
project label, they will have set a project before doing the include,
and then my project will interfere and not be the target project they
think they're using.
        b) ? nothing good here I suppse
    2) err (I don't understand why this works) but move include to the
end of the file?... and therefore within one of the projects  (this
particular family has 4 projects all in the same directory...) but it
works fine to include it at the end.

The following code however doesn't work as well at the end...

set(CMAKE_BUILD_TYPE "Debug" CACHE STRING
      "Set build type")
  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
               "Debug" "Release" "MinSizeRel" "RelWithDebInfo")

That code wants to be before the first project to work correctly.

I'm certain there's a very logical reason that things are where they
have to be... but I think I'm as confused as the other thread about
when things happen... I guess include is done before any other logic
is parsed?  what about if that include was in an If... and that if
depended on a condition of that (or another) included file?