Re: [boost] [serialization] using boost::serialization::collection_size_type and backwards compatibility

Subject: Re: [boost] [serialization] using boost::serialization::collection_size_type and backwards compatibility
From: Brian Ravnsgaard Riis (brian_at_[hidden])
Date: 2009-09-03 05:22:30

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

joaquin_at_[hidden] wrote:
> Matthias Troyer escribió:
>> On Sep 2, 2009, at 8:15 AM, joaquin_at_[hidden] wrote:
>>
>>  
>>> An observant colleague has noticed that Boost.MultiIndex serialization
>>> uses std::size_type instead of the adviced 
>>> boost::serialization::collection_size_type:
>>>
>>> https://svn.boost.org/trac/boost/ticket/3365
>>>
>>> My question is: if I just change std::size_type with
>>> boost::serialization::collection_size_type in Boost.MultiIndex 
>>> serialization code,
>>> will backwards compatibility be preserved, i.e. will users be able 
>>> to load
>>> archives saved with the old std::size_type variant? If not, what's 
>>> the suggested
>>> way to handle this issue?
>>>     
>>
>> The suggested way is to bump the version number of your class and 
>> check the archive version when deserializing
>>   
> 
> In  my particular case I'd have to bump the version number for a class
> *template*.
> Is there a documented way to do so, given that BOOST_CLASS_VERSION does
> work only for class instances?

namespace boost
{
    namespace serialization
    {
        template <typename T>
        struct version<YourTemplate<T> >
        {
            typedef boost::mpl::integral_c_tag tag;
            typedef boost::mpl::int_<'your version integer here'> type;
            BOOST_STATIC_CONSTANT(unsigned int, value = type::value);
        }
    }
}

Works for me. Tedious, I agree, but...

 /Brian Riis
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.12 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAkqfitYACgkQk1tAOprY6QEq+ACg6EYEZ03Vh8KskIq7W23zZgsD
zMoAoOL9/GbhqngnaNxR0q+WHqFcQhF3
=9Lq1
-----END PGP SIGNATURE-----