220 16407 article Path: news.gmane.org!not-for-mail From: Douglas Boffey Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Succinct declaration of metavariables Date: Thu, 19 Feb 2015 16:34:48 +0000 Lines: 99 Approved: news@gmane.org Message-ID: References: <36478d7e-8292-424d-9544-68de55ac0566@isocpp.org> <54E375C0.1000407@nasa.gov> <54E39CB7.9000309@nasa.gov> <18d594d0-270f-42ad-b0c0-7765ba688dc0@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1424363691 4511 80.91.229.3 (19 Feb 2015 16:34:51 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 19 Feb 2015 16:34:51 +0000 (UTC) Cc: jmckesson@gmail.com, ilja.j.honkonen@nasa.gov To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDSIZVXVVUFBBKFBTCTQKGQET76IYLA@isocpp.org Thu Feb 19 17:34:50 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f199.google.com ([209.85.214.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YOU3u-0003Xa-7e for gclcip-std-proposals@m.gmane.org; Thu, 19 Feb 2015 17:34:50 +0100 Original-Received: by mail-ob0-f199.google.com with SMTP id nt9sf62347931obb.2 for ; Thu, 19 Feb 2015 08:34:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=pLUHpR8I9eEq7VDW9HZXzID6i2oFfBTRLHaTflmInBQ=; b=hSBMqQNltO3xBNitLl6neGa5j6VYLYcL1grXprSow5vLLorSoPJ6zkKKMYqjmMHnPm lXLVaS36K8M3zovao5m9MwldjtTwBNHKkj3fWpBuj+79ptShjflbacF2aWuj74BULhEt KVnu566QvyqwIcmXiNrujnjFdPleFeXPdlRFRUZ0NTNLePLB4kSf4VhcBLPMa/bcBe/T 46O0zK7isGy2g+cO258RhjSFReDlipx1RVatcNiiRIPucktt5o8x+CFPu9RUfGRF/OIV f3uDpvvFi/9GZAx/FnAQRK0cUSSP0vh7WGrPFP0ykbndFzdlTmaTs+lbPk8lwz5fmCXW mqXA== X-Gm-Message-State: ALoCoQkqR9qJH4LMf8C7BiapPEOiAwXUrRGKp7aJZzK5CUChdrwuWlin75kpg8V90DxAhqjtKwL0 X-Received: by 10.183.3.43 with SMTP id bt11mr5136188obd.7.1424363689297; Thu, 19 Feb 2015 08:34:49 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.33.1 with SMTP id i1ls773239qgi.34.gmail; Thu, 19 Feb 2015 08:34:48 -0800 (PST) X-Received: by 10.140.16.177 with SMTP id 46mr13119231qgb.22.1424363688581; Thu, 19 Feb 2015 08:34:48 -0800 (PST) Original-Received: from mail-qg0-x22c.google.com (mail-qg0-x22c.google.com. [2607:f8b0:400d:c04::22c]) by mx.google.com with ESMTPS id ku5si14308456qcb.23.2015.02.19.08.34.48 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Feb 2015 08:34:48 -0800 (PST) Received-SPF: pass (google.com: domain of douglas.boffey@gmail.com designates 2607:f8b0:400d:c04::22c as permitted sender) client-ip=2607:f8b0:400d:c04::22c; Original-Received: by mail-qg0-f44.google.com with SMTP id j5so7395883qga.3 for ; Thu, 19 Feb 2015 08:34:48 -0800 (PST) X-Received: by 10.140.89.111 with SMTP id u102mr13321797qgd.20.1424363688288; Thu, 19 Feb 2015 08:34:48 -0800 (PST) Original-Received: by 10.140.100.135 with HTTP; Thu, 19 Feb 2015 08:34:48 -0800 (PST) In-Reply-To: <18d594d0-270f-42ad-b0c0-7765ba688dc0@isocpp.org> X-Original-Sender: Douglas.Boffey@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of douglas.boffey@gmail.com designates 2607:f8b0:400d:c04::22c as permitted sender) smtp.mail=douglas.boffey@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: 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:16407 Archived-At: Or namespace Here::Is::A::Very::Long { Typename a = ...; Typename b = ...; Typename c = ...; // etc } On 2/19/15, Nicol Bolas wrote: > > > On Tuesday, February 17, 2015 at 2:55:23 PM UTC-5, Ilja Honkonen wrote: >> >> > I don't know whether the ability to avoid typing the keyword double >> > >> was >> > a conscious decision (in K&R or before, after?), if it wasn't then I >> > >> > agree that this probably wouldn't be worth the apparently large >> effort, >> > but if it was then similar reasoning might apply here. >> > >> > Typenames aren't restricted to just "double". They can be long, >> > arbitrary, and unwieldy namespace-qualified things. While "using" is >> > always 5 characters long. >> >> If I understood your argument correctly the same applies to regular >> variables: float is always 5 chars long while the value assigned to each >> variable can come from a long, namespace-qualified, etc. function. >> > > ... what? > > My point was that what you're saving in the variable case is itself > *variable*. That is, it changes from case to case. The difference is this: > > Here::Is::A::Very::Long::Typename a = ...; > Here::Is::A::Very::Long::Typename b = ...; > Here::Is::A::Very::Long::Typename c = ...; > Here::Is::A::Very::Long::Typename d = ...; > > vs. > > Here::Is::A::Very::Long::Typename > a = ..., > b = ..., > c = ..., > d = ...; > > In this case, you're saving a lot of keystrokes. With your "metavariable" > case, the only thing you save is typing "using" for each variable. That's a > > far smaller number of keystrokes. > > So there's just not much of an incentive to having it in the language. > > >> >> > Also, I don't particularly agree with putting multiple variable >> > definitions in a single statement to begin with. It's certainly terse, >> > but it's needlessly terse. Plus, it doesn't work well with 'auto', which >> > >> > is what a lot of my variable definitions are using nowadays. >> >> Mine too and in cases where several variables are of the same type a >> single auto shows that quickly. In the syntax I propose the same would >> hold for template arguments given before using which might also improve >> readability. >> > > That constitutes an actual use case, as it saves more than just typing a > keyword. > > You should lead with that next time. > > Granted, I still don't consider it a good idea. But it would actually be > something useful. > > -- > > --- > 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. > Visit this group at > http://groups.google.com/a/isocpp.org/group/std-proposals/. > -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. .