220 4301 article Path: news.gmane.org!not-for-mail From: Lawrence Crowl Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A cleaner way to define nested class/structure Date: Tue, 7 May 2013 11:52:49 -0700 Lines: 139 Approved: news@gmane.org Message-ID: References: <27175469-a158-4bc1-9f30-66e3a647e931@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1367952777 26320 80.91.229.3 (7 May 2013 18:52:57 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 7 May 2013 18:52:57 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCY3D77DYUDBBA43UWGAKGQE25EVNXI@isocpp.org Tue May 07 20:52:58 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ve0-f197.google.com ([209.85.128.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UZn0O-0007zC-Lq for gclcip-std-proposals@m.gmane.org; Tue, 07 May 2013 20:52:52 +0200 Original-Received: by mail-ve0-f197.google.com with SMTP id jz10sf1236336veb.4 for ; Tue, 07 May 2013 11:52:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlers.com; s=googlers; h=x-received:x-beenthere:x-received:received-spf:mime-version :x-received:in-reply-to:references:date:message-id:subject:from:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-google-group-id:list-post :list-help:list-archive:list-subscribe:list-unsubscribe:content-type; bh=eXURiLgUXFoX6vv/NHo/gEVrBN/nG6e40ytq28EokFM=; b=IkeOO1L+GQ1u3TEQRYXGhDIOdEHH/uRqL7Py1RBqt9fHquXFsCGvdLZM+Ygt3fBOVH 93ZfkGzbTDSacF0eBxmWBYjbN4EcnFQ1vmAsyvHMfFXLnxaLQoXZhJcQdFb+dCJUteur LKNwjtg6XAcXDhsAidc6mhA9Wcdg6OmzF3b30= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:x-beenthere:x-received:received-spf:mime-version :x-received:in-reply-to:references:date:message-id:subject:from:to :x-gm-message-state:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-google-group-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=eXURiLgUXFoX6vv/NHo/gEVrBN/nG6e40ytq28EokFM=; b=kVNP3LxmdYp1JJaLjphH0/h3nwSk2zDWJrS9a1PFGwH7ICDDDqJosDJkeTSLuub6ng icnObyTDZc2GEvXbI5E3PfS1QuAtUltkpQ4H+53UHjZe7pGOKx4PFLJXGYbOZ2+mKnnd DgOgEvJlUhSfW9KhW3710jlpcpNLYeoww9l+xpFu5n7mWM/fRVRp0XBQQdFHvd/M5p/E TOfA92MIdEEkEB2F1gsNcRSNrxy351NDINtlnijQfdDVA1LWlnOxlofA4toXq6MjIwFT M2LZ0vjd7KMNoHEMNKUYYgLTfw0eDMQ X-Received: by 10.236.140.99 with SMTP id d63mr2120703yhj.6.1367952771733; Tue, 07 May 2013 11:52:51 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.14.9 with SMTP id l9ls523183qec.97.gmail; Tue, 07 May 2013 11:52:50 -0700 (PDT) X-Received: by 10.49.71.165 with SMTP id w5mr2693944qeu.36.1367952770686; Tue, 07 May 2013 11:52:50 -0700 (PDT) Original-Received: from mail-qa0-x22b.google.com (mail-qa0-x22b.google.com [2607:f8b0:400d:c00::22b]) by mx.google.com with ESMTPS id w8si18924014qag.88.2013.05.07.11.52.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 07 May 2013 11:52:49 -0700 (PDT) Received-SPF: pass (google.com: domain of crowl@google.com designates 2607:f8b0:400d:c00::22b as permitted sender) client-ip=2607:f8b0:400d:c00::22b; Original-Received: by mail-qa0-f43.google.com with SMTP id bs12so2309636qab.9 for ; Tue, 07 May 2013 11:52:49 -0700 (PDT) X-Received: by 10.49.85.131 with SMTP id h3mr2704733qez.42.1367952769437; Tue, 07 May 2013 11:52:49 -0700 (PDT) Original-Received: by 10.229.197.13 with HTTP; Tue, 7 May 2013 11:52:49 -0700 (PDT) In-Reply-To: X-Gm-Message-State: ALoCoQlCDUKjBQpDRcv8Mpk40G9lBdUV+22R8XDgEwvU9gBPkqzK28yDG+fo9YC9IpaG1dQlG70N3bySk2PD7cFtRfxwnlRlRUkwI6AIOhf8utbCfs1JkN8jc2mQm5x4nNLKLCtgH53GeQCjZcl0TGzlciTKfinNzZxmIFgiFeqhFtOVtGD6xhstMdyB+mfXOeqS2Ozn3DVa X-Original-Sender: crowl@googlers.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of crowl@google.com designates 2607:f8b0:400d:c00::22b as permitted sender) smtp.mail=crowl@google.com; dkim=pass header.i=@googlers.com; dmarc=pass (p=NONE dis=none) d=googlers.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:4301 Archived-At: On 5/1/13, Hariharan Subramanian wrote: > Iteration 2: > > class Outer; > > class Outer::Inner1 { > int i; > }; > > Outer::Inner1 *i1; > //The above should result in compilation error. Because we do not know yet > if Inner1 is private or public > //even though we are just declaring a pointer. It should wait till we > define the Outer class. > > class Outer { > public: > class Inner1; //non-declaration of this should be a compilation error > class Inner2; > > private: > Inner1 inner1; //No issues > Inner2 *inner2; //No issues > }; > > class Outer::Inner2 { > int j; > }; > > Outer::Inner1 *i1; //No compilation error because we know that it's public > > -------- > > Because Inner1 is usable outside only after the Outer class is defined > there should be no other change to the language specification. That is a good improvement. > > Regards, > Hariharan S > > > > On Tue, Apr 30, 2013 at 11:19 PM, Lawrence Crowl > wrote: > >> On Apr 29, 2013 Lawrence Crowl wrote: >> > Why isn't the following solution sufficient? >> > >> > class Outer { >> > class Inner1 { >> > int i1; >> > }; >> > class Inner2; >> > Inner1 inner1; >> > Inner2 *inner2; >> > }; >> > >> > class Outer::Inner2 { >> > int i2; >> > }; >> >> On Apr 29, 2013 Hariharan Subramanian wrote: >> > It is sufficient but I think it is incomplete. I am able to define >> > a nested class outside as long as I have a pointer/reference >> > variable. This proposal completes it by giving the ability to >> > define the nested class outside even if we have an object. This >> > improves readability. This is as good as (or as bad as) the >> > existing one. >> >> On 4/30/13, Tony V E wrote: >> > It isn't very nice when Inner1 is large. >> > >> > Same with inline member functions - you can define them inside the >> > class, but sometimes it is nicer to define them after the class >> > (yet still in the header, still inline). The only difference with >> > inner classes would be that you would need to define them first. >> > >> > You see similar things in boost libraries that use the >> > boost::detail namespace. (There are other reasons to put stuff >> > in boost::detail, inner classes is just one.) >> >> Okay, so you two have two reasons, useful generality and readability. >> Now we need a discussion of any potential language ambiguities, the >> costs of implementation, and eventually wording changes to the >> standard. All of this should be collected into a formal paper for >> a meeting. The next one is in Chicago this fall, but the committee >> might be extra busy getting C++14 out, so were I you, I would shoot >> for the meeting after that. >> >> -- >> Lawrence Crowl >> >> -- >> >> --- >> You received this message because you are subscribed to a topic in the >> Google Groups "ISO C++ Standard - Future Proposals" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/a/isocpp.org/d/topic/std-proposals/l865qYE3Wa8/unsubscribe?hl=en >> . >> To unsubscribe from this group and all its topics, 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/?hl=en. >> >> >> > > -- > > --- > 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/?hl=en. > > > -- Lawrence Crowl -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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