Re: [Boost-users] [Boost.Serialization] (De-)serialization with class versioning

Subject: Re: [Boost-users] [Boost.Serialization] (De-)serialization with class versioning
From: james (dirtydroog_at_[hidden])
Date: 2018-03-11 16:35:39

On Sunday, March 11, 2018, james <dirtydroog_at_[hidden]> wrote:

>
>
> On Sunday, March 11, 2018, Lars Ruoff via Boost-users <
> boost-users_at_[hidden]> wrote:
>
>> Hi,
>> i use the class versioning feature of Boost.Serialization, with an
>> external (non-intrusive) serialization function like this:
>>
>> BOOST_CLASS_VERSION(GAMEINFO, 1)
>>
>> template <typename Archive>
>> void serialize(Archive &ar, GAMEINFO& gameSettings, const unsigned int
>> version)
>> {
>> ar & gameSettings.NPODS;
>> // ...
>> if (version > 0)
>> ar & gameSettings.ARENA_GOAL_EXCLUSION_RADIUS;
>> }
>>
>> Now as soon, as i set BOOST_CLASS_VERSION(GAMEINFO, 1), i get version==1
>> in this serialize function, even when i *deserialize* (load from archive).
>> I would have expected to get the version of the data in the saved archive
>> in this case.
>>
>> Say i saved with an old version=0.
>> Then my class evolved and i set BOOST_CLASS_VERSION(GAMEINFO, 1).
>> But when reading the old archive, i expect version==0 in the function so
>> i can react on it.
>> Instead, i get always version==1, as soon as i compile with
>> BOOST_CLASS_VERSION(GAMEINFO, 1), even when i'm reading old files!
>> What am i missing?
>>
>> regards,
>> Lars R.
>>
>>
>
> You're not missing anything based on my similar experience. We ended up
> not using the version functionality because it turned out to be useless. It
> made rolling out code changes a tedious affair, which if not choreographed
> carefully would lead to deserialisation changes in the best case, and
> crashes in the worst. We plan to drop boost serialisation entirely.
>
> Maybe someone will point out what we're both doing wrong.
>

I meant to type 'deserialisation exceptions' instead of 'deserialisation
changes' above