From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fac41,9a0ff0bffdf63657 X-Google-Attributes: gidfac41,public X-Google-Thread: 1108a1,9a0ff0bffdf63657 X-Google-Attributes: gid1108a1,public X-Google-Thread: f43e6,9a0ff0bffdf63657 X-Google-Attributes: gidf43e6,public X-Google-Thread: 103376,4b06f8f15f01a568 X-Google-Attributes: gid103376,public From: doylep@ecf.toronto.edu (Patrick Doyle) Subject: Re: Which wastes more time? (Was Re: Software landmines (loops)) Date: 1998/09/09 Message-ID: #1/1 X-Deja-AN: 389519488 X-Nntp-Posting-Host: spark23.ecf Sender: news@ecf.toronto.edu (News Administrator) References: <35F56290.AB5491D9@s054.aone.net.au> <35F6C4BF.404D6A68@s054.aone.net.au> Organization: University of Toronto, Engineering Computing Facility Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada Date: 1998-09-09T00:00:00+00:00 List-Id: In article <35F6C4BF.404D6A68@s054.aone.net.au>, Loryn Jenkins wrote: >Patrick Doyle wrote: >> >> class PERSON >> feature >> name: STRING >> age: INTEGER >> end >> >> class CAR_OWNER inherit PERSON >> feature >> cars: ARRAY [CAR] >> end >> >> CAR_OWNER is a subtype of PERSON. In the portion of the report >> that lists everyone's age, this polymorphism is important. > >You're starting to hint at it, but haven't said it yet: What would you >imagine these two abstractions being used for in this imagined >application? > >Be a little more specific: give me an example. Oh, now I understand. Sorry. Suppose the report listed an employee's allowances. PERSON might have a command called list_allowances. Whatever PERSON does in this command, CAR_OWNER would extend it by adding a section for car allowances. Does this suffice? If not, then perhaps my problem is that I don't see where you're going by arguing that this is not a "real" subtyping relationship. Could you explain that a bit more? -PD -- -- Patrick Doyle doylep@ecf.toronto.edu