[Boost-build] defaulting address-model and instruction-set

Subject: [Boost-build] defaulting address-model and instruction-set
From: Sebastian Hauer (sebastian.hauer_at_[hidden])
Date: 2008-12-08 10:30:16

Hello,
I was just wondering if there was some way to feature default
address-model and instruction-set?  I am only building for a limited
set of architectures.  And on 64 bit machines I would like to default
to address-model : 64 and instruction-set : nocona ?
I have a few if statements to detect the environment and set two
variables base-address-mode and base-instruction-set which I use in
the top level project like this:

project
    : requirements
        <address-model>$(base-address-model)
        <instruction-set>$(base-instruction-set)

It all works just fine the project builds for 64bit as expected but
now my build variant output path is two levels deeper, e.g.:

bin\msvc-8.0\debug\address-model-64\instruction-set-nocona\

I've tried adding:

feature.set-default address-model : $(base-address-model) ;
feature.set-default instruction-set : $(base-instruction-set) ;

to make them the address-model-64\instruction-set-nocona\ directories
go away but with no luck.  I've done something similar for for multi
threading which worked out nicely but for some reason I can't default
address-model and instruction-set.  Any ideas?

Thanks,
Sebastian