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!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Confused about class-wide types Date: Sun, 20 Mar 2016 15:26:10 +0100 Organization: Aioe.org NNTP Server Message-ID: References: <86oaa97635.fsf@gaheris.avalon.lan> <86fuvl6yjt.fsf@gaheris.avalon.lan> NNTP-Posting-Host: LMk7+sG0YqgPmReI4fVkAA.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:29834 Date: 2016-03-20T15:26:10+01:00 List-Id: On 2016-03-20 14:58, Mart van de Wege wrote: > "Dmitry A. Kazakov" writes: >> BTW, it is a bad idea to use pointers, as bad as using vectors for a >> FIFO or Unbounded_String to keep constant strings. To dynamically >> allocate Unbounded_String which contents is again dynamically >> allocated is quite bizarre. Pointers could be used with queues when >> messages are pre-allocated elsewhere, in order to avoid copying >> overhead. > > Yeah, but when I want to have a number of different Event types with > some common operations that I want to store in a Vector, Variant record is also an option, but not for strings. > I either need > pointers, or, as Shark8 points out, an Indefinite_Vector, which I > overlooked. A vector is still not a ring buffer / FIFO. If messages are large you might use handles/pointers to the reference-counted object. The FIFO holds handles instead of objects. That prevents multiple copying on enqueue/dequeue. Upon enqueue you increase the count, upon dequeue you decrease it. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de