Re: [Boost-users] auto_link question

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-10-02 22:44:31

Hmmm - but why is it a mistake?

Robert Ramey

Rene Rivera wrote:
> 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.