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,bbd357da6d6d7756 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-01-05 19:49:15 PST Path: archiver1.google.com!news2.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news.airnews.net!cabal12.airnews.net!usenet From: "John R. Strohm" Newsgroups: comp.lang.ada Subject: Re: How to? Writeable from a readable? Date: Sun, 5 Jan 2003 21:39:30 -0600 Organization: Airnews.net! at Internet America Message-ID: X-Orig-Message-ID: References: <3T2S9.721$GU4.33144@newsfep1-gui.server.ntli.net> Abuse-Reports-To: abuse at airmail.net to report improper postings NNTP-Proxy-Relay: library2.airnews.net NNTP-Posting-Time: Sun Jan 5 21:48:09 2003 NNTP-Posting-Host: ![.ps1k-X'iHMlI (Encoded at Airnews!) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Xref: archiver1.google.com comp.lang.ada:32597 Date: 2003-01-05T21:39:30-06:00 List-Id: Maybe I'm way out in left field here. In capability-based operating system terms, it sounds as though you are trying to take a read-only capability and amplify it into a read-write capability. Every capability system I ever saw was specifically designed to prevent you from doing precisely that: if the owner of the object wanted you to have read-write access to the, he would have granted you a read-write capability for the object in the first place. What I think you want to do is go back to the original system, structure it as a read-write object, and then make a read-only view of it that you give out to the world. Only the ones who really have a legitimate need for read-write access get the read-write capability. "chris.danx" wrote in message news:3T2S9.721$GU4.33144@newsfep1-gui.server.ntli.net... > Hi, > > How can you resolve the following problem? Let's suppose you have a > tagged type readable_x say, which only allows you read access to the > data in it, and you want to extend it with a new tagged type writeable_x > which allows you read and write access to data. How can you do this? > > > The problem as I see it, is that if you make the data in readable_x > private you can't extend and modify it in the extended type, but if you > make it public anyone can modify the data anyway. Is there a way around > this problem (I want to allow a writeable wherever a readable is allowed!)? > > > Cheers, > Danx > -- > for personal replies change spamoff to chris >