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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 Path: border1.nntp.dca3.giganews.com!backlog3.nntp.dca3.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!goblin3!goblin1!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Safety of unprotected concurrent operations on constant objects Date: Thu, 15 May 2014 18:30:18 +0200 Organization: cbb software GmbH Message-ID: References: <83ha6vuynrzs.1jk08faxb8mnl.dlg@40tude.net> <1jebi7cf92ak4.1trmstj8qi3wm.dlg@40tude.net> <1i6pyg077xlrv.vnwotzzgb0ut$.dlg@40tude.net> <10pk27v48vhcb$.1qkf6roq2yzjn$.dlg@40tude.net> <1qq0ryc8c4l2m.1driqwwiwwl02.dlg@40tude.net> <%vhcv.255737$s87.168969@fx11.iad> <1tb8my720vum2$.r9u7r03btzqm.dlg@40tude.net> <8w0te2yerch4$.1ll2fpovfkuzx.dlg@40tude.net> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: AuYlnUSfTZrfhAkRjyySpQ.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 X-Original-Bytes: 3390 Xref: number.nntp.dca.giganews.com comp.lang.ada:186431 Date: 2014-05-15T18:30:18+02:00 List-Id: On Thu, 15 May 2014 11:53:09 -0400, Robert A Duff wrote: > "Dmitry A. Kazakov" writes: > >> Because inability to prove that contract X is fulfilled by a party P makes >> P illegal. [*] > > I know that's your point of view. I haven't seen you explain why. Sorry? There are three outcomes of a proof: 1. True 2. False 3. Don't know And two outcomes of program legality: A. Legal B. Illegal Now map 1,2,3 to A,B. I assume it is: 1 -> A 2 -> B 3 -> B (cannot prove it, assume it is wrong) You? > Yeah, I know compile-time checks are good when possible. > But they're not always possible (as I'm sure you know). > So insisting on contracts being checked at compile time > doesn't make my programs better -- it just requires me to > put "--" before some of my contracts. ? We were talking about a prover, at least I was. I fail to see how a prover could be related in any form to run-time. You may say that prover is not about pseudo-contracts of Ada 2012, I don't care. Use whatever word you want, but prover is still a compile-time. >> Unless you accept making illegal programs legal, you must not allow the >> prover's power to change. > > Every new version of Ada has made some previously-illegal programs > legal. An infinite number of them, in fact. So of course I > accept making illegal programs legal. If you are OK with that, very well. Still you will have to mandate a well-defined power within each version. Otherwise, legality will depend on the compiler. P.S. I thought you were against making function Foo return Integer is begin raise Constraint_Error; end Foo; legal? -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de