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=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Extend slices for n dimensional arrays for Ada 202X Date: Sat, 28 Jan 2017 10:08:54 +0100 Organization: Aioe.org NNTP Server Message-ID: References: NNTP-Posting-Host: s3c6wwRqkurrfTZpuYYZ+w.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:33207 Date: 2017-01-28T10:08:54+01:00 List-Id: On 2017-01-28 00:37, Randy Brukardt wrote: > ... general slices really don't fit very well into any type model since they're > a different shape (in general) than the originating array type. It depends on the slice. When some dimensions are collapsed the result is a different but related type. When all dimensions are retained the type is same (or equivalent). You consider a scenario where the array and its "full" slice have the same representation like in Ada 83. It would mean either keeping actual constraints in the object (bad) or else providing a universal mechanism of user-defined constraints passed along with the object. [Generic user constraints] Another method is using a class-wide operation where both array and slice are expected. Slice would be a sibling type of different representation, both array and slice derived from the same abstract parent. P.S. My vision of ideal Ada is when its type system would allow moving built-in arrays and records into the specification of the package Standard. [Tagged types should have had nothing to do with record types.] -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de