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,FREEMAIL_FROM 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!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: Victor Porton Newsgroups: comp.lang.ada Subject: Re: Type invariants and private extensions? Date: Tue, 12 Sep 2017 21:54:08 +0300 Organization: Aioe.org NNTP Server Message-ID: References: <364ff8e0-c7dd-4980-b19f-5d438edd8353@googlegroups.com> <7df81b3c-1fde-4395-8b9b-1a945820a7f7@googlegroups.com> NNTP-Posting-Host: qUTqmJlZKcITHxg9FVl9Fw.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit X-Complaints-To: abuse@aioe.org User-Agent: KNode/4.14.10 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:48080 Date: 2017-09-12T21:54:08+03:00 List-Id: Jeffrey R. Carter wrote: > On 09/12/2017 12:02 AM, Victor Porton wrote: >> Isn't it a good idea to modify the RM to allow type invariants also for >> derived types with null records? > > Not unless you have a real problem that can't be solved otherwise. I do have: A SPARQL query may return boolean, graph, bindings, etc. The return type is determined by the text of the query. I want to make derived types of a query which are validated that their return is of a certain type (e.g. a boolean). This certainly useful in a language like Ada intended for reliability and maximum runtime check during debugging. I could make them just private extensions instead of null record extensions, but after this I would be forced to manually make a derived version of every constructor function for the derived type. It appeared as a real practical problem in my research. -- Victor Porton - http://portonvictor.org