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 X-Google-Thread: 103376,547e6c7b9fae4e1d X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-01-23 07:09:22 PST Path: archiver1.google.com!news1.google.com!sn-xit-02!sn-xit-06!sn-xit-09!supernews.com!iad-peer.news.verio.net!news.verio.net!fu-berlin.de!uni-berlin.de!tar-alcarin.cbb-automation.DE!not-for-mail From: Dmitry A. Kazakov Newsgroups: comp.lang.ada Subject: Re: Instanciation in a package spec. Date: Thu, 23 Jan 2003 16:13:46 +0100 Message-ID: <8d103vca385t457d6p2e8uch8qe8p706g7@4ax.com> References: NNTP-Posting-Host: tar-alcarin.cbb-automation.de (212.79.194.111) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: fu-berlin.de 1043334561 29127411 212.79.194.111 (16 [77047]) X-Newsreader: Forte Agent 1.8/32.548 Xref: archiver1.google.com comp.lang.ada:33375 Date: 2003-01-23T16:13:46+01:00 List-Id: On Thu, 23 Jan 2003 14:19:49 GMT, Robert A Duff wrote: >"Jean-Pierre Rosen" writes: > >> "Robert A Duff" a �crit dans le message de news: wccel752ki5.fsf@shell01.TheWorld.com... >> > "Grein, Christoph" writes: >> > >> > > > * GNAT 3.15p issues: >> > > > pascalhe.ads:135:03: warning: cannot instantiate "Ad_hoc" before body seen >> > > > pascalhe.ads:135:03: warning: Program_Error will be raised at run time >> > > >> > > Believe Gnat. It's a RM rule to forbid instantiations before elaboration of the body. >> > >> > A very annoying rule, indeed. >> > >> ???? >> Since the body of the instance is elaborated at the point of instanciation, the body of the >> generic has better been elaborated already.... > >I understand the *need* for the rule in Ada. But it's still an annoying >restriction. It's perfectly reasonable to want to export a generic and >an instance of that generic from the same package. But Ada's >elaboration model prevents it. > >It's also annoying that you can't call a function in the same package: > > package P is > function F(...) return T; > X: constant T; > private > X: constant T := F(...); -- raises P_E. > end P; > >The problem here is the elaboration model of Ada. The *visibility* of >things is too closely tied to the *elaboration* order. I have worked >out a different model of elaboration that doesn't have this problem (but >still retains all the advantages of the Ada model). Unfortunately, it's >not Ada. Why it cannot become Ada? In other words, what is the price of your model? Can X become static (in your model), when F is pure? --- Regards, Dmitry Kazakov www.dmitry-kazakov.de