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: non record limited type Date: Fri, 23 Feb 2018 09:58:15 +0100 Organization: Aioe.org NNTP Server Message-ID: References: <3a2e91d4-f563-4843-9c80-5a76732626d3@googlegroups.com> 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 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 X-Notice: Filtered by postfilter v. 0.8.3 Content-Language: en-US Xref: reader02.eternal-september.org comp.lang.ada:50588 Date: 2018-02-23T09:58:15+01:00 List-Id: On 23/02/2018 00:24, Randy Brukardt wrote: > "Dmitry A. Kazakov" wrote in message > news:p6luqm$jb1$1@gioia.aioe.org... >> On 22/02/2018 02:29, Randy Brukardt wrote: >> >>> These types that become limited just because of "limited private" also >>> have >>> the nasty property of becoming non-limited when you can see the full >>> declaration. This causes all kinds of semantic complications that we'd >>> rather not repeat, so everything new requires declaring it limited >>> explicitly and staying that way. >> >> I don't see anything wrong with that, except for coupling to by-reference >> semantics. On/off visibility of the copying operation is all OK, it is >> just an operation. Parameter passing method is a different thing. > > Not to Ada: by-copy uses the assignment operation (which isn't quite the > same thing as :=). Limited assignment is build-in-place only (for > initialization purposes, another rule I know you hate). Probably could be > different, but it would take extra work, and so far, there doesn't seem to > be much need. Right, but by-copy passing is not really assignment. It is a copy-constructor. When assignment finalizes the target, copy-constructor does not do anything. Ideally we should be able to disable ":=" while keeping by-copy passing. I can imagine use cases for short-lived smart pointers and iterators where I wanted no explicit copies made. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de