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 01:02:59 +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:48023 Date: 2017-09-12T01:02:59+03:00 List-Id: Isn't it a good idea to modify the RM to allow type invariants also for derived types with null records? Jere wrote: > On Monday, September 11, 2017 at 5:27:54 PM UTC-4, Victor Porton wrote: >> Egil H H wrote: >> >> > On Monday, September 11, 2017 at 10:48:46 PM UTC+2, Victor Porton >> > wrote: >> >> > The Invariant will then be inherited by all derived types >> >> >> >> It is not what I want. I want different invariants for different >> >> derived types. >> >> >> > >> > You can add new invariants in addition to the ones inherited >> >> I cannot: the compiler gives an error: >> >> package P is >> >> type T is tagged private; >> >> private >> >> type T is tagged null record; >> >> end P; >> >> with P; use P; >> >> package P1 is >> >> type T1 is new T with null record >> with Type_Invariant => True; >> >> end P1; >> >> >> $ gnatgcc -gnatc -c p1.ads >> p1.ads:6:10: aspect "Type_Invariant" only allowed for private type or >> corresponding full view >> >> -- >> Victor Porton - http://portonvictor.org > > You aren't applying it to a private type. Try: > > package P1 is > > type T1 is new T with private > with Type_Invariant'Class => True; > > private > > type T1 is new T with null record; > > > end P1; > > The relevant RM section: > > 7.3.2 > > 2/3 > Type_Invariant > > This aspect shall be specified by an expression, called an > invariant expression. Type_Invariant may be specified on a > private_type_declaration, on a private_extension_declaration, > or on a full_type_declaration that declares the completion of > a private type or private extension. > > 3/3 > Type_Invariant'Class > > This aspect shall be specified by an expression, called an > invariant expression. Type_Invariant'Class may be specified > on a private_type_declaration or a private_extension_declaration. -- Victor Porton - http://portonvictor.org