Re: [boost] Re: [serialization] automatic linking andintrusiveserialization support

From: JOAQUIN LOPEZ MU?Z (joaquin_at_[hidden])
Date: 2005-02-08 19:10:26

----- Mensaje original -----
De: Robert Ramey <ramey_at_[hidden]>
Fecha: Miércoles, Febrero 9, 2005 0:20 am
Asunto: [boost] Re: [serialization] automatic linking 
andintrusiveserialization	support
[...]
> fJOAQUIN LOPEZ MU?Z wrote:
[...]
> > So far so good. Boost 1.33 release of Boost.Serialization,
> > if I'm not wrong, will include automatic linking, and here comes
> > the problem: when doing the upgrade to 1.33, user2 will be
> > delighted that he'll no longer need to do the linking stuff by
> > himself;
> 
> > but user1 will get mysterious "not found" linking errors,
> > or worse yet, he'll have Boost.Serialization automagically
> > bundled into his final executable, when he never explictly
> > dealed with this lib in the program!
> 
> I don't believe this is the case. Templated code is not emitted unless
> explictly invoked.  If user2 never serializes anything the then 
> the member
> serialization template won't be expanded.  This view is supported 
> by the
> fact that if serialization isn't used - then no *_iarchive.hpp 
> file is
> included so the template argument Archive has no known value so its
> impossible for the compiler emit the code.
> 

I think I'm not explaining myself clearly. I agree
with you that user1 won't cause any serialization-related
code to be emited by the *compiler*. The problem is that,
by virtue of the internal #include <boost/serialization/access.hpp>
in foo.h, he will get Boost.Serialization autolinked,
because <boost/serialization/access.hpp> (or some other
serialization header, don't know precisely) ultimately
includes auto_link.hpp.
In other words: he will stumble upon Boost.Serialization
binary without ever explicity mentioning or trying to
use this library.

At the risk of repeating myself, try compiling the
following:

#include <boost/serialization/access.hpp>

int main(){}

If I'm correct, autolinking will kick in yet the program
does not use Boost.Serialization at all. Of course
the program has included a serialization header so it
should face the consequences, but in the problem I describe
that header is included internally and the user
who won't be using serialization capabilities shouldn't be
forced to explicitly disable autolinking.

Get my point? If so, and if you agree with my analysis,
do you think the workaround I propose would work?

Thank you,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo