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 X-Received: by 10.50.128.226 with SMTP id nr2mr165802igb.2.1418692228568; Mon, 15 Dec 2014 17:10:28 -0800 (PST) X-Received: by 10.140.81.169 with SMTP id f38mr686210qgd.3.1418692228536; Mon, 15 Dec 2014 17:10:28 -0800 (PST) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newspeer1.nac.net!border2.nntp.dca1.giganews.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!h15no22424193igd.0!news-out.google.com!r1ni53qat.1!nntp.google.com!w8no8291321qac.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Mon, 15 Dec 2014 17:10:28 -0800 (PST) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=206.53.78.59; posting-account=ShYTIAoAAABytvcS76ZrG9GdaV-nXYKy NNTP-Posting-Host: 206.53.78.59 References: User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <4f547857-ea9e-4baf-a705-911fbf9c633d@googlegroups.com> Subject: Re: Access parameters and accessibility From: sbelmont700@gmail.com Injection-Date: Tue, 16 Dec 2014 01:10:28 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Xref: news.eternal-september.org comp.lang.ada:24028 Date: 2014-12-15T17:10:28-08:00 List-Id: >=20 > Could someone give an example/explanation where this rule is used? > I tried to read the RM. Chapter 3.10.2 seems to be the right one but I=20 > don't understand it either... >=20 As others have pointed out, anonymous access types are 'expert friendly' at= best, and there is a whole host of history and compromises as to why they = are how they are, most of which are obsolete in 2012. For 99% of situation= s, you don't have to lose any sleep over any of this (though I disagree wit= h the 'never ever ever' attitude of others). However, long story short, using an 'access parameter' (i.e. an anonymous a= ccess type as a subprogram parameter) requires passing along some meta-data= about the object for various esoteric situations when a runtime check migh= t be required. However, as the author points out, there are some (even rar= er) cases where what would normally require a runtime check would be static= ally known to be ok, and thus could be performed without risk. That's all = it's saying. This is compiler detail, not a language rule, so I would doubt you would fi= nd it in the LRM (perhaps in the AARM, as a note?) If you are a masochist,= the same author produced a whitepaper back in the day going into much more= gory detail about all this (ACM Ada Letters, Jan/Feb 1995, page 45 specifi= cally). -sb