[CMake] Are the [Project name]_SOURCE_DIR variables stored in the cache ?

[Nils Gladitz]

On 01.05.2014 20:38, Glenn Coombs wrote:
> Okay, I think I understand what you're saying.  Variables set in a 
> CMakeLists.txt file added by add_subdirectory are only visible in that 
> CMakeLists.txt and any further ones it adds via add_subdirectory.  The 
> higher level CMakeLists.txt files would not have the necessary 
> visibility, hence the need to cache the project source directory 
> variable.  To make it behave consistently it would be necessary for 
> cmake to be able to set a variable in the scope of the top level 
> CMakeLists.txt.  Similar to the PARENT_SCOPE that the set() command 
> already has, something like set(foo_SOURCE_PROJECT "path/to/source" 
> ROOT_SCOPE).
>
> I suspect that the reason cmake is caching these variable is because 
> the set() command doesn't have a ROOT_SCOPE ability and using cache 
> variables was the easiest way to simulate that.  And we have to live 
> with the unfortunate side effect that the cached variables don't exist 
> on the first run but do on subsequent runs.
>

I don't think it would be sufficient to set it in the root scope either 
since I think each scope has its own copy of the variable.
It would have to be set for all scopes between the root and the current 
scope.

Nils