[boost] [Serialization] How to retrieve a class version in an archive without loading?

Subject: [boost] [Serialization] How to retrieve a class version in an archive without loading?
From: nico (nicolas.guillot_at_[hidden])
Date: 2013-10-18 08:01:45

Hello.

My question is about program rollback and the management of archive
compatibility :
let's say I saved on object of type T with my program in version 1.35 =>
archive.txt.
If I roll back my program to a previous version (let say 1.30), I'd like to
check (without trying to deserialize for performance issue) if T in 1.30
has the same "BOOST_CLASS_VERSION" as the object saved in archive.txt.

*In brief : is there a way to retrieve the BOOST_CLASS_VERSION of T stored
in the archive ?*

I read boost code, but I didn't find a "quite direct" way to do that.
It seems I must get cobject_id_vector of basic_iarchive_impl, but all this
stuff is private.
Is their another non-intrusive way to do it ? (By non-intrusive I mean :
only using the boost public stuff, or at least with a simple inheritance to
get protected member of base classes?).

Thanks in advance.

nicolas.