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
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