[Boost-build] Basic bjam issues

Subject: [Boost-build] Basic bjam issues
From: Alexander Sack (pisymbol_at_[hidden])
Date: 2008-10-08 16:06:36

Hello:

I'm using FreeBSD 6.1-amd64, bjam 3.1.12, as well as boost-1.34.1.

I experimenting with using bjam for medium sized project and having
trouble with some basic concepts.  The project is obviously
hierarchical with several libraries built which are then used to build
some binaries etc. etc, nothing really out of the ordinary.

Here are so far my issues:

- If my Jamroot file defines a variable why isn't this global across
the project?

e.g.
Jamroot:
my_var  = something ;

some_project/Jamfile
echo $(my_car) ;

is empty!

- Why can't I use multiple build variants?  I want to be able to build
my project with certain features defined (i.e #define's).  If I try to
define a build variant for each one via:

variant feature_support1 : <define>feature1 ;
variant feature_support2 : <define>feature2 ;

etc.  I want to be able to turn them on and off from bjam command line

- I have a set of include files that need to be defined for some of
the modules within my project.  So I don't want to put an
<include>blah in the top level Jamroot file, i.e. I want to define a
alias or variable that I can substitute on some of my target rules to
use this include.

I tried the alias approach in the doc like so in my top-level Jamroot file

alias common_includes : : : : <include>blah <include>blah1 ;

etc.

But this doesn't work.  I can't seem to use it in any of my sub
modules source lines nor can I use it in the usage-requiremetns.  I
then tried to use a simple variable and shell substitution but that
let me to my first question.

Any help would be much appreciated (the doc is killing me!),

-aps