[boost] Hybrid compilation model? was: [system] Why is this not header-only?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2007-04-06 10:57:06

There has been a thread running with the subject "[system] Why is this 
not header-only?" that discusses header-only versus compiled-library 
compilation models for Boost libraries.

Some users require the compiled-library approach. I'll characterize 
these folks as requiring the shorter compile times and better software 
engineering practice that compiled libraries provide. In some cases 
these folks have had to rework Boost header-only libraries to create 
compiled libraries.

Some users prefer the header-only approach. They need to be able to 
quickly set up at new project without messing around with compiled 
libraries. They want to be able to evaluate Boost libraries without 
doing any preparatory work altogether.

Jeff Garland and Andrey Semashev argued that Boost should adopt a hybrid 
compilation model that allows applicable Boost libraries to be used in 
either header-only or compiled-library modes. Note that Boost.Test 
already provides this, although with degraded functionality in 
header-only form.

There was some discussion as to how to do this; my eyes glazed over when 
discussions drifted into problems of dlls, singletons, etc.

I'll like to challenge Boosters to think about this problem a bit more, 
and I'd love to see someone who understands the challenges take, say, 
Boost.System and demonstrate how it could be packaged for either 
header-only or compiled-library use. The important goal would be to 
abstract what to done into a general set of guidelines (and any 
configuration support needed). In other words, we don't so much need a 
solution for Boost.System as for any Boost library that would benefit 
from a hybrid computation model.

Comments?

--Beman