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: 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 X-Google-Thread: fac41,2c6139ce13be9980 X-Google-Attributes: gidfac41,public From: doylep@ecf.toronto.edu (Patrick Doyle) Subject: Re: Separation of IF and Imp: process issue? Date: 1997/09/07 Message-ID: #1/1 X-Deja-AN: 270426263 Sender: news@ecf.toronto.edu (News Administrator) References: <33E9ADE9.4709@flash.net> 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: 1997-09-07T00:00:00+00:00 List-Id: In article , Jon S Anthony wrote: > >In article doylep@ecf.toronto.edu (Patrick Doyle) writes: > >> Spare me the psychoanalysis. I'm not interested in what mode of >> thought I'm caught in, and I don't think others are either. I'd >> just like an answer to my question. > >Hey, that's not "psychoanalysis"! ;-) Yes, I suppose my comment would have been more appropriate if you'd told me that my arguments reveal serious childhood scarring and a deep hatred of my father. :-) >> >An interface need not be involved in any >> >inheritance hierarchy. If you use abstract base classes as the means >> >to interfaces, then you are basically publishing a "contract" that >> >things derived from them will have the characteristics (methods and >> >whatnot) described in the base abstraction. If not, why even have it? >> >> True. The same is true of interface files, isn't it? > >OK, maybe the problem is I really don't know what you mean by >"interface file". For a spec. the answer is false. You can't derive >from it (though you can extend it in "arbitrary" ways via children) >and there's no inheritance. What's the difference between extending a spec with children, and deriving a subclass from an abstract class? >> >Different interfaces, OTOH, allows one to view a thing from completely >> >separate perspectives which may not be related in any way except >> >through an underlying implementation. >> >> Abstract base classes can accomplish this also, through multiple >> inheritance. > >The point is, the things are directly related via subclassing and >inheritance while this is not true for specs. As I see it, the body must have all the properties of the spec, and perhaps more. Ada does not use the term "inheritance" for this, but I think it's valid for Eiffel to do so. Don't you? If not, what is it about inheritance which fails to properly model the spec-implementation relationship? -PD -- -- Patrick Doyle doylep@ecf.utoronto.ca