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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,1116ece181be1aea X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-09-11 21:36:23 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!headwall.stanford.edu!newshub.sdsu.edu!elnk-nf2-pas!newsfeed.earthlink.net!wn14feed!wn13feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi.com!sccrnsc01.POSTED!not-for-mail Message-ID: <3F614D3A.2090805@attbi.com> From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Is the Writing on the Wall for Ada? References: <3F5F7FDC.30500@attbi.com> <3F6079A9.6080108@attbi.com> <3F60E380.4020307@attbi.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 24.34.139.183 X-Complaints-To: abuse@comcast.net X-Trace: sccrnsc01 1063341382 24.34.139.183 (Fri, 12 Sep 2003 04:36:22 GMT) NNTP-Posting-Date: Fri, 12 Sep 2003 04:36:22 GMT Organization: Comcast Online Date: Fri, 12 Sep 2003 04:36:22 GMT Xref: archiver1.google.com comp.lang.ada:42400 Date: 2003-09-12T04:36:22+00:00 List-Id: Hyman Rosen wrote: > Stephen Leake wrote: > >>> But type inheritance cannot be from two concrete parents, no matter >>> what the language--one parent has to be abstract. >> >> >> You and I and many others understand this; still others do not. > > > That is an argument which is ridiculous on its face, so perhaps > you can explain the deep meaning that makes it so? > > The simple counterargument is that when you choose to implement > more than one interface in a class, it's possible, and even likely, > that there already exist concrete classes which implement all or > part of those interfaces in a way which is suitable for what you > need, and therefore your class can inherit from more than one of > these concrete classes to gain those implementations for free. I was going to answer your comment above, but this makes it obvious you must have some other definition in mind for inheriting from a concrete class than direct inheritance. How about an example of inheriting from two concrete classes? I could suppose you are talking about mix-ins, but Ada already supports MI for mix-ins, and since Ada will support interface inheritance from more than one interface, it can't be that either. -- Robert I. Eachus "As far as I'm concerned, war always means failure." -- Jacques Chirac, President of France "As far as France is concerned, you're right." -- Rush Limbaugh