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: fac41,2c6139ce13be9980 X-Google-Attributes: gidfac41,public X-Google-Thread: 1108a1,2c6139ce13be9980 X-Google-Attributes: gid1108a1,public X-Google-Thread: f43e6,2c6139ce13be9980 X-Google-Attributes: gidf43e6,public X-Google-Thread: 103376,3d3f20d31be1c33a X-Google-Attributes: gid103376,public From: doylep@ecf.toronto.edu (Patrick Doyle) Subject: Re: Separation of IF and Imp: process issue? Date: 1997/09/05 Message-ID: #1/1 X-Deja-AN: 270005353 X-Nntp-Posting-Host: skule.ecf Sender: news@ecf.toronto.edu (News Administrator) References: <33E9ADE9.4709@flash.net> Organization: University of Toronto, Engineering Computing Facility Newsgroups: comp.object,comp.software-eng,comp.lang.ada,comp.lang.eiffel Date: 1997-09-05T00:00:00+00:00 List-Id: In article , Matthew Heaney wrote: >In article , doylep@ecf.toronto.edu (Patrick >Doyle) wrote: > >>>But this is not quite the same thing as the relationship between a module >>>specification and its body. >> >> Ok, I'll boil my position down into one question: What does a separate >>interface file do for a class that an abstract superclass can't do? > >True, an abstract superclass would specify the characteristics common to >every subclass in that derivation tree, but an interface file ("package >spec") describes the characteristics of a specific class. And this limitation is an advantage somehow? >The module interface is separate from its body, and can therefore be >configured separately. Any changes to the spec have to be coordinated with >the clients of the package. If this separate configuration is important, an abstract superclass could be used, couldn't it? You nkow what? I just thought of an argument against myself here. Tell me what you think... If abstract superclasses are used as interfaces to a class, then they are optional. Thus, the advantages of tracking spec changes come only when the programmer *chooses* to track them. Conversely, *all* spec changes will necessitate alteration of clients, so arguably *all* classes should have a spec that is somewhat harder to change. For Eiffel not to enforce this can cause maintenance troubles down the road. -PD -- -- Patrick Doyle doylep@ecf.utoronto.ca