Re: [Boost-users] [serialization] Richer "tagged" fields andpolymorphic archive types

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-11-14 14:29:55

Using NVP as a model is a good start and good decision.
But I see your problem.
Take the following with a large grain of salt as I'm really just speculating 
without really thinking.
instead of handling FIELD as a member function in your archive like xml 
archives to with NVP, consider the following:

a) make a FIELD wrapper similar to make_nvp - I assume you've already got 
this. Note that you should set the new "is_wrapper" trait described in the 
latest version 1.35 checked in to the HEAD branch. This will permit the 
FIELD type to pass through the compile time traps which detect unwise 
behaviour. Alternatively, you can disable the compile time trap. See the 
last section in "Rationale" regarding the compile time trap.

b) implement serialization for objects of FIELD type in more or less the 
normal way. Use NVP as a model. This will permit serialization of your FIELD 
with any archive. I don't know if you've done this yet

c) Make your own archive .... but DON"T do what xml_archive does with NVP. 
That is, don't include an override for FIELD in the archive class itself.

d) make your own specializations for the function template serialize. 
(Assuming non-intrusive serialization here), (Assuming compiler supports 
partial function template ordering correctly).
template<class T>
void serialize(tibco_oarchive & ar, field<T> &t, const unsigned int 
version){
... // special stuff for "field"
}
and
template<class T>
void serialize(polymorphic_tibco_oarchive & ar, field<T> &t, const unsigned 
int version){
... // special stuff for "field"
}

note that this code can be included in your header "field.hpp" so that is 
seen when and only when you're using FIELD.
This will move the "extra specical sauce" for FIELDS on the tibco_oarchive 
to inline code BEFORE it even gets the polymorphic archive itself. There 
could be a problem with start/end though.

"I'm building at my place of work as a more flexible replacement for Rogue 
Wave's "saveGuts/restoreGuts"."

Wow - I wish I'd thought of THAT name.

Robert Ramey