[Boost-build] Multiple calls to "using boost" with the same version

Subject: [Boost-build] Multiple calls to "using boost" with the same version
From: Anthony Foglia (AFoglia_at_[hidden])
Date: 2009-06-11 21:29:52

        In our project we have a sysdefs.jam file at the top of the directory 
structure that sets up the rules for most of the libraries.  I just 
replaced the 200+ lines we had for boost libraries with aliases to the 
boost libraries as defined in the boost.jam file that comes with boost.

        While working up to this change, I set up a user-config.jam of my own 
to set up boost.  Very simple, configures both the system version of 
boost 1.35, and a version of 1.38 I downloaded and compiled in my home 
directory.

        When I changed our repository code, since we haven't been using 
site-config.jam, I put a "using boost" rule in our sysdefs.jam file 
(located in the same directory as our Jamroot).  Bjam complained that 
"Boost 1.35 already configured."

        I patched boost.jam to test for duplicate initializations, and if the 
new settings are the same as the old, do nothing.  (And print a warning 
if .debug-configuration is set.)

        Is there a better way?  Should/Can I test before calling "using boost" 
in the sysdefs to see if it's been defined earlier (e.g. 
user-config.jam)?  Should/Can I catch the error instead?

-- 
Anthony Foglia
Princeton Consultants
[phone] x233