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: Interface/Implementation (was Re: Design by Contract) Date: 1997/09/13 Message-ID: #1/1 X-Deja-AN: 272192341 Sender: news@ecf.toronto.edu (News Administrator) References: <34167245.0@news.uni-ulm.de> X-Nntp-Posting-Host: skule.ecf Organization: University of Toronto, Engineering Computing Facility Newsgroups: comp.object,comp.software-eng,comp.lang.ada,comp.lang.eiffel Date: 1997-09-13T00:00:00+00:00 List-Id: In article , Matt Austern wrote: > >doylep@ecf.toronto.edu (Patrick Doyle) writes: > >> Close, but IMO no cigar. If we are faithfully to compare Ada and >> Eiffel ways of doing this, then just as an Ada package is accessed >> through its interface, so would the Eiffel class be accessed only >> through the abstract superclass. Thus, even if the subclass >> added public features, the client couldn't use them. > >Except that that's impossible. You have to know the name of the >derived class, and the signatures of its creation functions, in order >to create objects of that class. So the interface of the derived >class cannot be completely hidden. Right, we can't create an object without using its creation features. Beyond that, we can go through the abstract interface. The trouble is, I don't know if what I just said makes sense, because I can't imagine a reason to want to restrict interface extension. -PD -- -- Patrick Doyle doylep@ecf.utoronto.ca