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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no 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: Exclusive file access Date: Mon, 7 Sep 2015 21:06:17 +0200 Organization: cbb software GmbH Message-ID: <9pmm48f38rj5.os8vtdtxiti.dlg@40tude.net> References: <75714e3f-c047-413d-9aa5-3ff423167863@googlegroups.com> <1440837116.20971.33.camel@obry.net> <87oahpovpn.fsf@mid.deneb.enyo.de> <87y4gsmut1.fsf@mid.deneb.enyo.de> <87zj179n7n.fsf@mid.deneb.enyo.de> <87fv2qw0cx.fsf@mid.deneb.enyo.de> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: KtjLDd4WMA73P86fmkCmKw.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:27735 Date: 2015-09-07T21:06:17+02:00 List-Id: On Mon, 07 Sep 2015 20:27:58 +0200, Florian Weimer wrote: > * Dmitry A. Kazakov: > >> Anything you can encode in Unicode you can encode in Unicode. > > This is simply not true across multiple Unicode versions (and when > dealing with multi-byte encodings). Versions of Unicode are irrelevant. > It is not possible to express all > possible UCS-2 sequences in UTF-32, in the sense that converting from > UTF-32 completely covers the entire set of UCS-2 strings. You can represent all code ranges in UTF-32. I don't think the language should care about "visible characters." This insanity can be safely ignored. >>> The user may select a file, but the application cannot open it. >>> That's a poor user experience. >> >> That is not a problem at all. You cannot create a 999TB large file either. > > Well ... > > -rw-r--r-- 1 fw fw 1098412116148224 Sep 7 20:23 t > > And I expect that I can delete it, too. Anything else would be a bug. Bug of the OS or of your program? Ada.Text_IO could also tell you that the file was created and then proclaim anything else a bug. >> System-specific constraints put on an implementation do not effect the >> interface, which has Name_Error in it already. > > It's not a constraint that the system imposes, it's something that > requires careful thought from the programming language implementor. You cannot have files named ".." on some OSes. That has nothing to do with Ada or any other language. > If they impose stronger constraints on strings than what the file > system enforces, you end up with non-nameable files and a poor user > experience. That is the problem with current Ada.Directories and Ada.Text_IO. Not because of a constraint, but because the constraint is meaningless in a system that allows wider sets of characters than ASCII. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de