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 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED.3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: How to transfer Class-Wide object to a Task ? Date: Mon, 14 Oct 2019 21:58:34 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <5da4cf81$0$20312$426a74cc@news.free.fr> NNTP-Posting-Host: 3d73Ybk3C5U4I2t8lv+lAQ.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.9.2 Xref: reader01.eternal-september.org comp.lang.ada:57279 Date: 2019-10-14T21:58:34+02:00 List-Id: On 2019-10-14 21:41, William FRANCK wrote: > Here is a nice issue I have with Ada (GNAT 2012) when trying to do OO > dispatching with streams in different tasks ... > > Here it is : > I'd like to get from a task RdV (Entry-Access) an object which could be > any subclass of a root'Class, and pass it to another task > > Context : read (Root'Class'Input() ) tagged records from an input > stream, and send them to anther task which will write > (Root'Class'Output() ) the given records to another output stream. Strange design, why not to pipe streams using a FIFO? > I'm stuck with task memory isolation with does NOT allow to pass any > access object to a Root'Class. > > Should I try to use a protected object ? > (not shore this solves the passing of a Class-wide object ...) Yes, if using FIFO, a protected object can be used to signal non-empty/not-full events at the FIFO ends. Otherwise, use a reference-counted handle or a plain access type to the target object. The reader task allocates the object in the pool and passes a handle or access to it to the writer. The writer task writes the object and then disposes it. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de