Re: [Boost-users] auto_link question

From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2006-10-02 21:31:32

Robert Ramey wrote:
> When I build the serialization library I get two copies of the diagnostic 
> message.
> 
> I asked this before but now I can't find the answer.  It seems that it was
> suggested that this was symptom of some sort of mistake that could/should
> be corrected.  In studying this I've come upon the following scenario.
> 
> 
> library ab contains
> 
> a.cpp - with interface in a.hpp
> b.cpp - with interface in b.hpp
> 
> User programs might contain a.hpp or b.hpp or both
> depending on what they want to call.  So each of
> a.hpp and b.hpp should contain auto-link to generate
> the pragma corresponding to the library ab.  However
> if, it the user includes both a.hpp and b.hpp - which
> he gets two diagnostic messages - since auto_link.hpp
> has no include guard.  If this is a mistake, where is it
> and who is making it?

Well I'd say it's a mistake of the author of a.hpp and b.hpp. From 
looking at the thread version of autolink it uses a common header for 
doing the configuration. That config header, which includes the autolink 
header, is guarded. Hence you get only one message. I don't see this in 
the autolink author guidelines though.

The rationale for autolink.hpp not being guarded is of course that it 
needs to be included multiple times. In the same way that some of the 
Boost.PP headers work.

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