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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,9d3353604f79501f X-Google-Attributes: gid103376,public From: Robert Dewar Subject: Re: Task Problem Date: 1999/04/11 Message-ID: <7eqja4$pf8$1@nnrp1.dejanews.com>#1/1 X-Deja-AN: 465133809 References: <004601be8271$a408ad60$a20eb4d8@dhoossr> X-Http-Proxy: 1.0 x12.dejanews.com:80 (Squid/1.1.22) for client 205.232.38.14 Organization: Deja News - The Leader in Internet Discussion X-Article-Creation-Date: Sun Apr 11 16:40:38 1999 GMT Newsgroups: comp.lang.ada X-Http-User-Agent: Mozilla/4.04 [en] (OS/2; I) Date: 1999-04-11T00:00:00+00:00 List-Id: In article , "David C. Hoos, Sr." writes: > -----Original Message----- > From: Sean Hill > To: chat@gnat.com > Date: Thursday, April 08, 1999 4:03 PM > Subject: Task Problem > > >Any thoughts out there? > > > I know this is not a first step when porting from > Ada83 to Ada95, but I have found no need for the > rendezvous mechanism in any of my new > designs, and have changed many rendezvous designs > to use protected queues. Certainly this is possible, but it inevitably ends up with a lower level design. This is because protected objects are extremely restrictive in what they can do, they are not a general Ada building block. In any protected object, you have to know whether any procedure you might call is potentially blocking, something you don't know from the spec. We find people writing a LOT of invalid code in which protected objects do in fact make blocking calls, and we know at least one user who absolutely depends on this behavior. That's a bit worrisome. Obviously a rendezvous can be implemented as efficiently as a protected object interaction in a similarly restricted case (that is what passive tasks were all about in some Ada 83 implementations), so efficiency is not really the issue here (from a language point of view). >From my point of view, some problems are more naturally solved with the RV, some with PT. The Burns and Welling Realtime book is a very nice source of considerations of various ways of using both constructions to solve typical RT problems. -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own