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!news.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Ada Annoyances Date: Tue, 27 Jun 2017 18:32:00 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <1ac5a44b-4423-443a-a7bb-2864d9abe78f@googlegroups.com> <1498048151.20885.28.camel@obry.net> <96174ea5-852d-44e9-8535-7c1eb24d5326@googlegroups.com> <8d3aff06-82df-485f-89e5-a50c326aab05@googlegroups.com> <66aa262e-2ac9-4016-b32d-e9fee14779e1@googlegroups.com> <88e2f18a-0786-4303-a5b8-fe82e8c81dcb@googlegroups.com> <71c4fdcd-4213-4b84-b852-c8674cfaf717@googlegroups.com> <0f43638d-8954-4db2-94a3-b6615754da34@googlegroups.com> NNTP-Posting-Host: MajGvm9MbNtGBKE7r8NgYA.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/52.2.1 Content-Language: en-US X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:47147 Date: 2017-06-27T18:32:00+02:00 List-Id: On 2017-06-27 17:19, AdaMagica wrote: > Am Montag, 26. Juni 2017 22:35:34 UTC+2 schrieb Maciej Sobczak: >> When executed, we get: >> >> test with Base >> call from Base's Initialize >> Hello from Base >> test with Derived >> call from Base's Initialize >> Hello from Derived <<<<<<< here are dragons! >> call from Derived's Initialize >> Hello from Derived > > Yes, this *is* a problem. No, it is misunderstanding of what Initialize procedure is. It is a class-wide constructor and not a type-specific constructor like in C++. This is per language design, willingly or not. Therefore it is OK to dispatch from Initialize because: 1. All components are initialized 2. Initialize is overrides If the intent is to use Initialize as a poor-mans substitute for a type-specific constructor, then you call parent's Initialize *and* you don't dispatch. If you use it as a class-wide constructor you can dispatch but you don't call parent's part. Usually parents class-wide subroutines can be used to factor out common initialization code. You can mix both approaches, but with utter care, because this is how mess starts. > The following uses *functions* instead (which behave more like C++'s constructors). Yes, if they return a specific type. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de