[Boost-build] [user-config.jam][stlport] how are toolset and stlib versions selected?

Subject: [Boost-build] [user-config.jam][stlport] how are toolset and stlib versions selected?
From: Andy Schweitzer (a.schweitzer.grps_at_[hidden])
Date: 2009-05-24 19:15:33

Can someone explain how tool usage gets resolved, given the following in 
user-config.jam?

In my command line I specify toolset=msvc-8.0~wm5~stlport5.2 and also 
stlib=stlport

How does bjam use those parameters to choose among all the possible 
using stlport statements in user-config.jam?

Here's my user-config.jam:

==========user-config.jam=============================
using stlport : 5.2.1 :
...

using msvc : 8.0~stlport5.2 :
...

using msvc : 8.0~wm5~stlport5.2 :
...

using stlport : 5.2~evc8~arm :
...

using stlport : 5.2~vc8~arm :
...

using msvc : 9.0~stlport5.2 :
...

using msvc : 9.0~wm5~stlport5.2 :
...

using stlport : 5.2~evc9~arm :
...

using stlport : 5.2~vc9~arm :
....
==========end user-config.jam=========================

It seems like the intention of multiple using statements is to allow 
something like "if I'm using msvc-8, use my stlport-vc8; if I'm using 
msvc-9-windows-mobile, use my stlport-vc9-windows-mobile, so the if we 
say toolset=mscv-9.0~wm5~stlport5.2 stdlib=stlport, the correct stlport 
should be found.

But bjam just seems to pick the first stlport using statement it finds.

How should the correct choice of stlport be implemented?

thanks

Andy