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 10.129.181.20 with SMTP id t20mr446790ywh.6.1502115041457; Mon, 07 Aug 2017 07:10:41 -0700 (PDT) X-Received: by 10.36.39.140 with SMTP id g134mr42388ita.7.1502115041420; Mon, 07 Aug 2017 07:10:41 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!border1.nntp.ams1.giganews.com!nntp.giganews.com!peer03.ams1!peer.ams1.xlned.com!news.xlned.com!peer03.am4!peer.am4.highwinds-media.com!peer03.iad!feed-me.highwinds-media.com!news.highwinds-media.com!s6no949741qtc.1!news-out.google.com!1ni1065itx.0!nntp.google.com!u14no962282ita.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Mon, 7 Aug 2017 07:10:41 -0700 (PDT) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=173.71.201.205; posting-account=QF6XPQoAAABce2NyPxxDAaKdAkN6RgAf NNTP-Posting-Host: 173.71.201.205 References: User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <24712b44-48d9-4763-a748-458b7b77d835@googlegroups.com> Subject: Re: Limited object by reference or access argument? From: Jere Injection-Date: Mon, 07 Aug 2017 14:10:41 +0000 Content-Type: text/plain; charset="UTF-8" X-Received-Bytes: 2352 X-Received-Body-CRC: 405488075 Xref: news.eternal-september.org comp.lang.ada:47632 Date: 2017-08-07T07:10:41-07:00 List-Id: On Sunday, August 6, 2017 at 5:16:37 PM UTC-4, Victor Porton wrote: > Suppose we have > > type World_Type is tagged limited private; > > type BNode_ID_Handler is abstract tagged limited private; > > We need to set a bnode handler for a world object. Should the procedure > signature be > > procedure Set_Handler (World: World_Type; > Handler: access BNode_ID_Handler'Class); > > or > > procedure Set_Handler (World: World_Type; > Handler: BNode_ID_Handler'Class); > > The later can work with limited BNode_ID_Handler type, because tagged and > limited types are always passed by reference. > > I prefer the second one, because with the first procedure signature it is > possible to pass an access to an already finalized object what is an error, > but want to ask you opinion which of the two procedure signatures is better. > > -- > Victor Porton - http://portonvictor.org You can also just make it tagged (Ada95 to present) or denote the procedure parameter as aliased (Ada2012): procedure Set_Handler (World: World_Type; Handler: aliased in out BNode_ID_Handler'Class); I am not sure of the limitations to that as it is a new feature I am less experienced with.