[Boost-build] Resetting set feature values.

From: Jurko Gospodnetiæ (jurko.gospodnetic_at_[hidden])
Date: 2007-10-29 10:04:31

   Hi.

   I have a few questions related to resetting already set feature values.

   One is whether it is possible for a master project to set a 
propagated feature value one way and then have a subproject (or a 
specific target) explicitly override this setting?

   Another question is whether it is possible to undefine a previously 
set C/C++ preprocessor define without getting two separate /Dxxx /Uxxx 
compiler options applied but instead have the undefine cancel out the 
previous define in the build system itself.

   A use case for this is preparing a project specific release variant 
which would not disable assertions like the built-in one does, but 
without having to explicitly duplicate the rest of the built-in release 
variant definition.

   Thanks in advance.

   Best regards,
     Jurko Gospodnetiæ