[Boost-build] Propagated feature that doesn't generate build directory

From: K. Noel Belcourt (kbelco_at_[hidden])
Date: 2007-12-06 00:54:18

Hi,

I got some libraries that depend on Lapack (optmized math kernels).   
On some systems there is no vendor supplied library so I need to  
build Lapack from source code, other systems have vendor supplied  
libraries I'd like to link against.  Here's my problem, I've created  
a feature:

feature lapack : vendor source : propagated ;

When I run bjam, I can select either lapack=vendor or lapack=source  
and everything works fine.  The only problem is that because the  
lapack feature is propagated, an entire new source tree (with lapack- 
source) is created when all I really want is to build one library  
from source and link it in (i.e. the lapack library doesn't introduce  
any kind of link incompatibility).  Removing the propagated attribute  
clearly won't build the lapack library from source code.

Is there another (combination of) attribute(s) that would propagate  
the lapack=source feature to all targets, but not cause any new  
directories in the build tree?

-- Noel

[ Here's the lapack jamfile ]

alias lapack
   :
   : <lapack>vendor
     <find-shared-library>lapack
   :
   : <lapack>vendor
     <find-shared-library>lapack
   ;

lib lapack
   : [ glob lapack/3.0/SRC/*.f
   : <lapack>source
   :
   : <lapack>source
   ;