[Boost-users] build times and Boost.Function

From: gast128 (gast128_at_[hidden])
Date: 2008-08-08 17:05:57

Dear all,

this would be my 3 post on build times and Boost, since we develop a fairly 
large system (> 3000 classes) and use Boost a lot. 

Rebuilding the complete system takes about 2 hours on my home pc (DELL P4 
2GHz, 512 Mb) and about 1 hour on my pc @ work (DELL G280, P4, ht, 3.0 GHz, 1 
Gb memory). We already use precompiled headers and tend to forward declare as 
much as possible.

Using some of the Boost components in headers is just out of the question 
because of the increased build times:
- exposing the Boost.MultiIndex headers in a much used header drammatically 
increases build times
- same argument for <boost/variant.hpp>
- including <boost/type_traits.hpp> give also a huge latency

However I also notice that Boost.Function does not have an include guard. 
Boost.Function is used a lot and exposed through a lot of headers in our code 
(since they often define a callback interface). Adding an include guard myself 
drops the build time for a test project dramatically if Boost.Function is 
included recursively:

- include guards + pch 0.42
- include guards       0.35
- normally             1.52

Is there a reason that <boost/function.hpp> does not have an include guard? 
Does it harm when adding one (or using a wrapper around it, 
i.e. "incboostfunction.h" which has an include guard)?

wkr.