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From: render@m.cs.uiuc.edu
Newsgroups: comp.object
Subject: Re: OO Languages with "constraints"
Message-ID: <77500008@m.cs.uiuc.edu>
Date: 25 Oct 89 00:11:18 GMT
References: <89@<GZA>
Lines: 9
Nf-ID: #R:<GZA:89:m.cs.uiuc.edu:77500008:000:486
Nf-From: m.cs.uiuc.edu!render    Oct 24 07:55:00 1989


Written 10:21 pm  Oct 21, 1989 by gza@mentor.cc.purdue.edu:
>If you always use methods to access instance variables, you can easily
>implement constrained instance variables in Smalltalk & Objective-C.

Yeah, but it's nice to make constraints declarative (i.e. height=width)
and have those things maintained automatically rather than encoding the
verification procedures by hand.  I think some relational DMBSs provide
this facility, and it's an interesting idea for OO PLs and DBMSs.