Re: [boost] ABI and API compatibility

From: Sebastian Redl (sebastian.redl_at_[hidden])
Date: 2008-04-24 11:56:24

Jens Seidel wrote:
> On Thu, Apr 24, 2008 at 12:37:09PM +0200, Sebastian Redl wrote:
>   
>> Any application that uses a precompiled 
>> Boost component probably uses other Boost components, too. As such, the 
>>     
>
> OK.
>
>   
>> likelihood is high that upgrading Boost means recompiling the 
>> application.
>>     
>
> Please explain this! Probably you mean that beside Boost libraries
> also parts of Boost are used which are provided in headers only?
> Now you assume that one has to recompile to gain from the header only
> parts? This is right but you forgot (if my assumptions are true)
> that there is a much more likely case:
>
> Every Linux or *BSD distribution (and probably also Cygwin and Fink)
> contains Boost and applications linked against it.
> Now assume the Boost maintainer in this distribution wants to
> update Boost. With a stable ABI the maintainer just uploads a new
> version of Boost and that's all. Without a stable ABI the maintainer
> either has to keep the old Boost library (or better librar*ies* in this
> case) and provide just another version or the upload of a new Boost
> version requires a coordinated upload with all recompiled programs and
> libraries which depend on Boost. This is a very big mess!!!!
>   
What I'm saying is that I believe it to be very dangerous to have your 
own application use Boost header-only libraries of one version and 
precompiled libraries that link against other versions of the 
header-only libraries. If components from the header-only version (say, 
a shared_ptr or an any) are somehow transferred between the main 
executable and the library, you're in great danger of crashing.
Great care would have to be taken that even the header-only libraries 
don't make changes that break such compatibility.

It depends on the kind of changes that go into point releases.

Sebastian