Re: [boost] Idea for discussion: Putting version number in boost namespace?

From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2008-04-27 17:41:45

Jonathan Biggar wrote:
> I noticed some discussion in threads about the worries that some people 
> have with linking their application against boost and then needing a 
> third party library that also links to a potentially different version 
> of boost that might not be available to the in source form.
> 
> Has any thought been given to changing the boost namespace declaration 
> to include the version number, like this:
> 
> namespace boost_1_35_0 {
> 	// boost libraries declared here
> };
> 
> #ifndef BOOST_NAMESPACE_ALIAS_DECLARED
> #define BOOST_NAMESPACE_ALIAS_DECLARED
> 
> namespace boost = boost_1_35_0;
> 
> #endif // BOOST_NAMESPACE_ALIAS_DECLARED
> 
> This allows an application linked to boost 1.X+1.0 to also link to a 
> third party library that privately uses boost 1.X.0 without causing ODR 
> problems.  Of course it doesn't help if the third party library exposes 
> boost types in its interface.
[...]

I was just discussing such a trick in the IRC channel in relation to the 
library building, and dealing with variants. The idea would be that 
instead of generating a bunch of different library files, we mangle the 
boost namespace name to include the variant one is using (which would 
include the version as you suggest). Using this would allow to build 
many variants, but still have the simple linking use pattern of 
"-lboost_foobar". Unfortunately it might not be possible to remove all 
separate library build, as many aspects of compiling affect ODR at the 
std level. As the discussions of the MSVC runtime options have illustrated.

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