[Boost-build] Setting environment variables

Subject: [Boost-build] Setting environment variables
From: Josh Stern (josh_at_[hidden])
Date: 2010-11-02 11:08:46

So far as I can gather from the documentation, there is no way to set OS 
environment variables from within boost build.    Is that correct?

It seems to me that it would be potentially useful to have such a 
feature, and not so hard to implement.    Here is a pseudo use case that 
it turns out I didn't currently need (relevant to recent messages about 
SDK7.1):

On MS-Windows, I like to use MingW type environment for building with 
Visual C++.    I use the msys version of bash to set relevant 
environment variables in my .profile, I launch the NT version of xemacs 
from the msys shell, and I call boost build from within xemacs.    I 
recently upgraded to the (downloadable) Visual C++ 2010 Express and 
installed the (downloadable) SDK 7.1 for the corresponding 64 bit 
compilers.   I like to do 32 and 64 bit builds side by side, mainly to 
help catch additional bugs.   After reading some messages to the list 
about patches needed for using SDK7.1, I was concerned that I wouldn't 
be able to easily run both 32 and 64 bit versions with current boost 
from within the same xemacs session.    Those concerns turned out to be 
unfounded, as it all seems to run fine in the same way as with VC++ 
2008, despite the presence of the alternative SetEnv scripts in 
SDK7.1.    However, this was just lucky.    It could turn out in the 
future that I would want to set environment variables from within boost 
build as a function of something like address-model.    Many tools use 
environment variables to communicate, just as others use command line 
parameters.   So it seems like a configurable build would benefit from 
supporting configuration of those communications.