How does it work when a class has been changed ?

Hi,

In OODBMS, class-based OO, suppose I save an object, then later modify
its class by removing/adding fields. Does it mean I cannot load the
old object ? How OODBMS handles this ?

Thank you

In the GemStone OODBMS, classes are first class objects. So when you
"modify" the class you are really creating a new version of the class. The
old instances are still instances of the old class until they are migrated
to the new version. And you can have instances of the old and new versions
of the class at the same time, although most people don't do this. In
practice, most people migrate all the old instances to instances of the new
version of the class.

Norm Green


"romerun" wrote in message

> Hi,
>
> In OODBMS, class-based OO, suppose I save an object, then later modify
> its class by removing/adding fields. Does it mean I cannot load the
> old object ? How OODBMS handles this ?
>
> Thank you
>