Re: [boost] Re: some thoughts about serialisation

From: Greg Colvin (Gregory.Colvin_at_[hidden])
Date: 2003-01-14 17:05:55

At 02:56 PM 1/14/2003, Dave Harris wrote:
>In-Reply-To: <3E2337F3.E78312AF_at_[hidden]>
>On Mon, 13 Jan 2003 23:04:35 +0100 Ares Lagae 
>(ares.lagae_at_[hidden]) wrote:
>> > How do you see archive versioning being done? For example,
>> > suppose field TOTAL is a double in version 1 and a
>> fixed-point user-defined type in version 2.

One answer is "don't do that."  Add a new field which can
be initialized from the old one, and stop using the old one.

>>
>> The easy way would be to let a class have multiple class descriptors 
>> (one for each version) and add the version number to the archive.
>
>That sounds rather coarse granularity. A class which evolved a lot would 
>have quite a few descriptors.
>
>Another approach would be to publish the changed field under a different 
>name, say TOTAL and TOTAL_2, in effect embedding version numbers into the 
>field names rather than the descriptor.