Re: [Boost-users] [serialization] Reading back old archives

Subject: Re: [Boost-users] [serialization] Reading back old archives
From: Robert Ramey (ramey_at_[hidden])
Date: 2010-07-11 19:16:39

David Raulo wrote:
> Hello,
>
> I have a problem reading back serialization archives generated by
> older version of boost. I used to have a YYYYMMDD class versioning
> scheme. This broke with boost 1.42, which truncates the class version
> numbers to 16 bits, causing my code to generated corrupted archives.
> I fixed my code by implementing my own class versioning when
> compiling with boost 1.42, so I am again able to create archives that
> I can read back. Unfortunately this fixes only half of the problem.
> How can I  read back archives that were saved using older releases of
> the serialization library?
>
> I saw that someone else opened ticket  3990 for the same problem.
> Here you suggested using the function get_library_version() in the
> following way:
>
> template<class Archive>
> void serialization(Archive & ar, unsigned int version){
>    library_version_type library_version = get_library_version
>    if(library_version < 6)
>        // the library version is a date
>        my_date = version;
>    else{
>        // don't use the boost serialization number, use ours instead
>        ar & my_date;
>    }
>    ar && old_data_items
>    if(ar.is_loading)
>       if(my_date > "jan 10, 2010")
>           ar & new_data_item;
>
>
> but I can't get this to work:  the version argument is already
> truncated, and can't be interpreted as a date. As the bug reporter
> said, this is a case of data loss.  Should I reopen ticket 3990, or
> is this code supposed to work with svn  (I admit I did not test the
> trunk)?

I've addressed this in the trunk and merged to release.  I took special
care to address situations such as your's.  BUT... , I
really haven't a good way to test this.  So I would be greatful
if you could download the lastest release version and verify that
this works as I believe it should.  If not, we should be able to
fix it.

Robert Ramey