Re: [Boost-users] undefined reference to base_object

Subject: Re: [Boost-users] undefined reference to base_object
From: John C (johnc_at_[hidden])
Date: 2010-05-03 11:36:44

Yeah, sorry, I suppose that sounds worse than what I intended. I guess what I
really mean is don't assume updates are backwards compatible...

Robert Ramey wrote:
> 
> John C wrote:
>  > I think this was the main cause of my problem, and this alone might
>> make it work in boost 1.40.0.
>> Since the header file that uses this is in a shared object file that
>> in some cases cannot have any boost dependencies, I had a forward
>> declaration for base_object. I had to remove the forward declaration
>> and #def in the inclusion of the boost export.hpp header for the
>> BOOST_SERIALIZATION_BASE_OBJECT_NVP macro.
> 
> It's hard for me to guess what's going to happen if you start messing
> with the header - especiallly if you only reveal this after the fact.
> 
> In order to limit dependencies, I would suggest a different technique.
> Don't use inline definiition.  Use the following in your class
> declaration:
> 
> template<class Archive>
> void serialization(Archive & ar, const unsigned int version);
> 
> In a *.cpp file define the template and explicitly instantiate it
> for the archive types that you use.  This will permit you
> to confine the inclusion of serialization library headers to
> a smaller set of files.
> 
> When using serialization code (or any template code) with DLLS
> this technique will also address another problem which is starting
> to come up - Multiple (and potentially conflicting) template
> instantiations.  This could lead to hellish debug scenarios as well
> as code bloat.  In some cases the library can now detect this
> problem, but I had to suppress the trap because it broke too
> much user code.  (That is, it detected too many problems in
> user code.)  When I have nothing else to do, I plan to revisit
> this and provide a trap that the user will be able to explicitly
> override.  It might not help, but at least the user won't be able
> to say he wasn't warned.
> 
>> The moral of the story:
>> If you are upgrading boost versions, don't assume the serialization
>> library hasn't changed drastically, especially if you are serializing
>> polymorphic types and even if it works fine in Windows.
>>
> 
> Well, the changes didn't seem drastic to me.  I think that is an
> overly harsh and missleading characterisation.
> 
>> Thanks for the help Robert....
> 
> Your welcome.
> 
> Robert Ramey
> 
> 
> 
> 
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> 

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