[CMake] Use of CMake OPTION in code

[Eric Noulard]

2008/10/21 Pelt, R.F.P. van <R.F.P.v.Pelt at tue.nl>:
>
> Dear all,
>
> Recently I have added an option to a CMake project that I'm using.
>
> For example:
> OPTION(BUILD_EXTRA_STUFF "Build extra stuff." ON)
>
> Whenever this is enables, this also changes a couple of things in
> the code, which is currently implemented with a hard define.
>
> For example:
> #define EXTRA_STUFF
> #ifdef EXTRA_STUFF
>
> Is there a way that I can 'propagate' the BUILD_EXTRA_STUFF option
> to my code, so that I can implements as follows:
>
> #ifdef BUILD_EXTRA_STUFF

May be you can try

IF(BUILD_EXTRA_STUFF)
    ADD_DEFINITIONS(-DBUILD_EXTRA_STUFF)
ENDIF(BUILD_EXTRA_STUFF)

note that since CMake variables and cpp MACRO are disjoint you may well

IF(BUILD_EXTRA_STUFF)
    ADD_DEFINITIONS(-DEXTRA_STUFF)
ENDIF(BUILD_EXTRA_STUFF)

such that you keep your current #ifdef EXTRA_STUFF
(but you may throw the hard code #define)

Another way to do it is to use a "config.h" file:

see
http://www.cmake.org/Wiki/CMake_HowToDoPlatformChecks


-- 
Erk