Newsgroups: comp.lang.smalltalk
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!news.sprintlink.net!mv!usenet
From: rapp@lmr.mv.com (L. M. Rappaport)
Subject: Re: URGENT: Schema evolution crucial question
Message-ID: <DCFCty.F2y@mv.mv.com>
Nntp-Posting-Host: lmr.mv.com
Sender: usenet@mv.mv.com (Paul Hurley)
Organization: MV Communications, Inc.
Date: Fri, 28 Jul 1995 14:49:08 GMT
References: <3uen66$b35@socrate>
X-Newsreader: Forte Free Agent 1.0.82
Lines: 20

lebel@cc.drev.dnd.ca (Eric Lebel) wrote:

>Is there any feature in smalltalk (or in VisualWorks - product we're using)
>to handle schema evolution of object classes over time.

It sounds like you are not storing your objects as objects, but
instead using a table handler with an RDBMS.  (if you stored them as
objects using an OODBMS you wouldn't have the problem)  That being the
case, I suppose that you could also include a column in the invoice
header table to indicate which methodology was used.  This could
always be added later and have your new invoice class select a method
based upon its state.

Larry
--





