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,LOTS_OF_MONEY autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,13703514e3723cbe X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-08-16 20:15:59 PST Path: archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!netnews.com!xfer02.netnews.com!newsfeed2.earthlink.net!newsfeed.earthlink.net!news.mindspring.net!not-for-mail From: "Brian Catlin" Newsgroups: comp.lang.ada Subject: Re: C-style 'union' in Ada? Date: Thu, 16 Aug 2001 20:14:24 -0700 Organization: Sannas Consulting Message-ID: <9li279$mhm$1@slb2.atl.mindspring.net> References: <9l7qon$d78$1@nntp9.atl.mindspring.net> NNTP-Posting-Host: a5.f7.f6.73 X-Server-Date: 17 Aug 2001 03:14:49 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4807.1700 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 Xref: archiver1.google.com comp.lang.ada:12030 Date: 2001-08-17T03:14:49+00:00 List-Id: "David Brown" wrote in message news:WUXe7.15629$ZM2.1376965@newsread2.prod.itd.earthlink.net... > Ted Dennison wrote: > > In article <9l7qon$d78$1@nntp9.atl.mindspring.net>, Brian Catlin says... > >> > >>I'm still trying to get both lobes around the Ada paradigm. I have a > >>record that I want to hold a pointer to a buffer which is either a String > >>or Wide_String, but I don't want to statically declare which, so using a > >>variant record won't work (at least given my understanding). Likewise, I > >>don't want to have two record definitions, one for String, and one for > >>Wide_String. In the package I'm designing, I don't care whether it is a > >>String or Wide_String, I will just pass it to the file I/O packages > >>(stream, in this case). In C, I would: > [...snip...] > > I have recently encountered a concrete example of the need for something > like this. The application is storing variable sized data fields in fixed > length records (say disk sectors). The block is defined as a large string. > The beginning of the block contains lengths for each of the variable sized > fields. The data items start at the end of the record and work their way > backward. > > Basically, there are two different views of the block and the boundary > between them depends on the sizes of the data items. > > Unchecked conversions of access values seems to be the easiest way to deal > with this. This is very similar to what I'm doing. I was trying to avoid unchecked conversion. I had assumed that there would be a better way. -Brian