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!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Comprehending subpools Date: Fri, 15 Jun 2018 09:15:00 +0200 Organization: Aioe.org NNTP Server Message-ID: References: NNTP-Posting-Host: MyFhHs417jM9AgzRpXn7yg.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:52.0) Gecko/20100101 Thunderbird/52.8.0 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.8.3 Xref: reader02.eternal-september.org comp.lang.ada:53114 Date: 2018-06-15T09:15:00+02:00 List-Id: On 2018-06-14 23:21, Randy Brukardt wrote: > The use case is situations when you have separable data structures that it > only makes sense to treat as a whole. Think of an expression tree in a > compiler. There are a lot of inter-structure links, so a reference counting > scheme for every pointer doesn't work. Rather, you can use a subpool and > only reference count the references to the entire tree. When that goes to > zero, you use the subpool to clobber the entire structure. Alternatively, > you might have weak references to the tree, that automatically get nulled > when the tree is clobbered. I think the questions rather were: 1. What is so special about arena or a mark-and-release pool that it cannot be handled by a user-defined pool in Ada 95? 2. Arena is inherently unsafe whatever implementation used. So all talk about "safety" does not make much sense. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de