Geometry Boost List: [ggl] Fixing Boost location in Jamfiles

Subject: [ggl] Fixing Boost location in Jamfiles
From: Mateusz Loskot (mateusz)
Date: 2010-03-09 18:14:08

Hi,

Barend, to follow up our talk we had on jabber, Volodya explained to
me the proper way of how to refer to Boost headers in Jamfile of
programs living outside Boost tree. The trick is to use <source> instead
of <include> for project in Jamfile.

The procedure to configure Boost environment and project Jamfile is:

1) Set user-config.jam with location of Boost

# For example, this points to my copy of Boost SVN trunk
use-project boost : D:/dev/boost/_svn/trunk ;

2) Jamfile of "test" project outside Boost tree

project test
    : requirements
    <source>/boost//headers
    ;
exe test1 : test1.cpp ;
exe test2 : test2.cpp ;

It is possible to set it per "exe" target too, this way:

exe test2 : test2.cpp /boost//headers ;

This way it looks for headers using absolute location combined this way:

"/boost//headers" is parsed as:

1) /boost

It means "boost" project location as configured in user-config.jam and
its location of D:/dev/boost/_svn/trunk

2) //

The  double forward slash means "Achtung! Now comes named target as
defined in "boost" project requested by /boost

3) headers

This is name of target.

Another example, if you need "test" library from boost project,
you can include it by referring to the "boost" project and corresponding
target, in similar way as above: /boost//test

So, if we set the <source>/boost//headers in Jamfiles of tests/examples
then users will be able to build them having the Boost.Geometry tree
outside Boost sources tree. I think it's a good idea to allow it
as it's convenient. I work like that myself having

/path/to/boost/svn/sandbox/geometry
/path/to/boost/svn/trunk

Once we move the Geometry to Boost tree, we can replace the
"/boost//headers" with relative paths as other Boost libraries do.
Specifically, we replace it with: <include>../../..

By doing that, we will assure that Boost Geometry is always built
using the same Boost headers with which our library was shipped.

But for now, we could allow to use Boost headers of user's choice,
using the location defined in user-config.jam.

I hope it makes more sense now :-)

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org