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=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,3a3dffa82925efee X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!news.glorb.com!cyclone1.gnilink.net!spamkiller2.gnilink.net!gnilink.net!nwrdny01.gnilink.net.POSTED!0e8a908a!not-for-mail From: Hyman Rosen User-Agent: Mozilla Thunderbird 0.7 (Windows/20040616) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Advantages References: <2k86nbF18idtrU1@uni-berlin.de> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: <3p5Ec.13759$Av3.4246@nwrdny01.gnilink.net> Date: Tue, 29 Jun 2004 03:32:15 GMT NNTP-Posting-Host: 68.161.132.92 X-Complaints-To: abuse@verizon.net X-Trace: nwrdny01.gnilink.net 1088479935 68.161.132.92 (Mon, 28 Jun 2004 23:32:15 EDT) NNTP-Posting-Date: Mon, 28 Jun 2004 23:32:15 EDT Xref: g2news1.google.com comp.lang.ada:1991 Date: 2004-06-29T03:32:15+00:00 List-Id: Randy Brukardt wrote: > It is a bounded error to use a blocking operation in protected > action (see 9.5.1(8-17)). It's defined to either be detected > (and raise Program_Error) or otherwise "may result in deadlock". > > Since GNAT detected the error at compile-time (thus the warning), there > couldn't be any run-time overhead for detecting the error. It should > therefore have raised Program_Error (allowing a known deadlock condition > seems like a very bad thing). But perhaps there is some customer of ACT's > that likes living dangerously? Or, perhaps the case just never came up, > because people rarely try to do the obviously bad... If I'm not mistaken, normal Ada I/O is potentially blocking and is therefore technically not allowed in protected actions. I believe ACT's customers found this to be too restrictive, and that's why GNAT doesn't prevent potentially blocking actions from being called. I seem to recall threads on this subject back when Dewar was still here.