[Boost-build] May I use conditions with define?

Subject: [Boost-build] May I use conditions with define?
From: Dmitry Timoshenko (dimentiy2k_at_[hidden])
Date: 2011-04-07 10:32:30

Hello,

may I write something like this in requrements section of the project 
(or lib rule)?

<define>UNICOMM_USE_COMPLEX_XML:<library>/smart//smart_data

if user passes to bjam define=UNICOMM_USE_COMPLEX_XML

I tried, but it doesn't matter... or may be it is possible to achive 
goal by another way?

Thank you.