From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-0.5 required=3.0 tests=BAYES_05 autolearn=ham autolearn_force=no version=3.4.5-pre1 Date: 7 Nov 92 01:25:34 GMT From: mole-end!mat@uunet.uu.net Subject: Re: OOD, Ada, and Inheritance Message-ID: <1992Nov7.012534.27855@mole-end.matawan.nj.us> List-Id: In article <1992Nov5.190921.21374@sei.cmu.edu>, wellerd@ajpo.sei.cmu.edu (David Weller) writes: > In article mmaccorm@fox.nstn.ns.ca (Mike Mac Cor mack) writes: > >If Ada software is being designed using OOA and OOD, should inheritance be > >avoided (or prohibited) in the design process, as Ada does not provide > >inheritance? > ... the Space Station Verification and Training Facility, is > applying both OOA and OOD. It is definitely a non-trivial project, ... > Our inheritance is "manual", ... pass-through calls and composition > to simulate "real" inheritance. ... we intend to quickly > transition to Ada 9X, ... In the 30 year life of this project, we > we felt that [this] would give bigger payoffs than [ignoring inheritance]. > It seems silly to sacrifice a design to fit in a current language. > Especially when you know that language will support those > "prohibited" features in about 2 years. I'd think that you'd want to distinguish between inheritance that models the problem, inheritance that models the solution, and inheritance as an implementation tool. Inheritance that models the problem is probably worth staying with, even at a high present cost and a high risk of subtle differences between your `simulation' and the actual feature. Inheritance that models the solution is probably economical only if it has a very high present value and if it will be flexible enough to be reimplemented cheaply with whatever version of inheritance is added to the language. Inheritance as an implementation tool is probably not worthwhile unless it confers a very strong and very specific architectural advantage. (Just my $0.02 worth ...) -- (This man's opinions are his own.) From mole-end Mark Terribile mat@mole-end.matawan.nj.us, Somewhere in Matawan, NJ