220 39871 article Path: news.gmane.org!.POSTED!not-for-mail From: David Brown Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: What do we want from named paramaters Date: Fri, 17 Aug 2018 19:16:03 +0200 Lines: 73 Approved: news@gmane.org Message-ID: References: <1534441498.3721109.1476442920.71D445BF@webmail.messagingengine.com> <2d91b5c9-da43-478c-b100-eed305f3397c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1534526111 13701 195.159.176.226 (17 Aug 2018 17:15:11 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 17 Aug 2018 17:15:11 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDP6R2XHXIARBHUG3TNQKGQE423R5DQ@isocpp.org Fri Aug 17 19:15:07 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lj1-f200.google.com ([209.85.208.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fqiL5-0003Sm-J1 for gclcip-std-proposals@m.gmane.org; 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Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1fqiL4-0003Q7-29 for std-proposals@isocpp.org; Fri, 17 Aug 2018 19:15:06 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 66 Original-X-Complaints-To: usenet@blaine.gmane.org In-Reply-To: <2d91b5c9-da43-478c-b100-eed305f3397c@isocpp.org> X-Original-Sender: david@westcontrol.com X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 195.159.176.226 is neither permitted nor denied by best guess record for domain of gclcip-std-proposals@m.gmane.org) smtp.mailfrom=gclcip-std-proposals@m.gmane.org Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:39871 Archived-At: On 17/08/18 17:25, Nicol Bolas wrote: > On Friday, August 17, 2018 at 11:09:38 AM UTC-4, David Brown wrote: > > On 16/08/18 19:44, Henry Miller wrote: > > > > > > > Third: > > class myString { > > int compare(myString, bool CaseSensitive); > > ... > > }; > > > > in code > > if(str.compare(otherString, false) == 0) ... > > > > // what does this mean, why would you call compare and not compare? > > > > This code is legal C++17, but it is user hostile. False in the > > context of reading the function makes no intuitive sense. Qt has > > created an enum for this, but it can be argued that this is too > > heavy. (you may or may not agree with the argument) > > > The ideal solution, IMHO, involves two parts. I would like to see > function parameter scope types, and perhaps be able to define them > within a function declaration. I want to see: > > class myString { > int compare( > myString, > enum class CaseSensitivity { insensitive, sensitive } > sensitivity > ); > > Then you could write: > > if (str.compare(otherString, insensitive) == 0) ... > > The "insensitive" would automatically be looked up in the scope of > types > declared within the scope of the function declaration. > > > That is an over-designed solution. The problem has nothing to do with > where the enumeration gets declared. Sticking the declaration in the > function signature doesn't really solve the problem. > > What solves the problem is the fact that the identifier `insensitive` is > looked up within the domain of how it is used. It's being used as a > function parameter that takes an enumeration which has an enumerator > called `insensitive`; therefore, that enumerator must be what it names. > > /That/ is the feature we need: the ability to take an identifier and > generate its "path" information based on context at the site of use. > This ability would aid in this problem and many others (enum-classes in > `switch/case`, having to prefix tags in tag dispatching with > `my_namespace::`, etc). > > There is no reason to wed context-specific "path" lookup to the location > where the particular thing is declared. Fair enough. It sounds like you are suggesting a more general solution that could be used in other places too. I'm happy with that idea. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/pl6vog%246qv%241%40blaine.gmane.org. .