220 27258 <8ee79066-43c5-4624-8fb5-01172eb36d29@isocpp.org> article Path: news.gmane.org!not-for-mail From: Sean Middleditch Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: loop continuation code Date: Mon, 25 Jul 2016 17:01:37 -0700 (PDT) Lines: 159 Approved: news@gmane.org Message-ID: <8ee79066-43c5-4624-8fb5-01172eb36d29@isocpp.org> References: <2f575934-e078-411c-9c8a-c2996da7609d@isocpp.org> <28358863-5be0-401a-893a-0ae5385156c2@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1277_712424841.1469491298070" X-Trace: ger.gmane.org 1469491304 24681 80.91.229.3 (26 Jul 2016 00:01:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 26 Jul 2016 00:01:44 +0000 (UTC) Cc: gmisocpp@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCDODCNR2QPRBY6Q3K6AKGQE56SDVKI@isocpp.org Tue Jul 26 02:01:44 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f200.google.com ([209.85.192.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bRpoc-0006ok-MP for gclcip-std-proposals@m.gmane.org; Tue, 26 Jul 2016 02:01:42 +0200 Original-Received: by mail-pf0-f200.google.com with SMTP id h186sf432859925pfg.3 for ; Mon, 25 Jul 2016 17:01:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Y6OTYc9CCS445r1beWWmoX8BR8p8+3s9soIFYebHzBA=; b=FiUkvo/HY1gci1tvNPMeIcPn5TEnaLmj/bNHFKe4MoGuubpSz0XI7+R1EZAxld8Bns +zaAZ6+bG0VyG680dEGkxwNXCgEnkB9mabGkvVMSadVSmdxuU4Z9PCunCqWvwYxpdB4B 8oNTbX3bZey7TdoaEkCueuy67MwJb8y/IfCrYfRr8v2BbasUs+o1g/UQLcCDbFZI8++Y guhKdQqLpjQsn71ZQJ3+fv/KLwIQhq5bStARWTwoi7vMDyZez3o2T00mLxmFqchBF9Aa kBLNGIns0N+F1q/UCZXoGXuHmZy1SAC+W3cd2v090exu1SC4WLXW+TGZ7szKUOEP99sE fjTA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Y6OTYc9CCS445r1beWWmoX8BR8p8+3s9soIFYebHzBA=; b=XFdAmvxLqo6SkpBkbA+cRTk4OmI9thwJJsWnhEm5Oii9d+Wu2LyxjWJXaDjbtOuj9b BLPPCfauVd6KRiCaapK9BKQe0NJoUkW5N5FTBQ32bZ6sKkWNCjIcefks0oS9C9vnxLmw MBaAz2YYMjCveBTEnggLdvNUgMH2eleKJeUA5xC781oT47RIx1MdHVqsHQWmOl9QhDQn wSWpewiQaY+nxG+XffE0UOmVB21eFtqROt2oIFgdATemle89XfmHRV2mrc6iqQ6IwXbh HPq0RAOk9EZZESOSNhSG8YVkvnHCrZ7eNRtX3F1TXqt2jxKS1e4MeE9Tj2cnvC5VL02R uczQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:x-original-sender:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=Y6OTYc9CCS445r1beWWmoX8BR8p8+3s9soIFYebHzBA=; b=T84IaVhdRzlbYavRzovFpQ86G9oIn/kE7YUauU1+mkg7nOv2TBPM4pHdAZxMxT9TsP AAJ/QGEUidKUKhdY2fPJUeRW5k9EPtiIaEBx4RDglj3ZAPc32gjDMbfu0IStKFNNoykS 63s/z/KuLmDkPwjmSe/0Mg+0n6gf3JLy5EBBCJnSoFStFDriesRt6j6V53NlaMtfKcjy GwJOio99JQAROxPXVZHUKlX13cI9GcpMEGy/I+nf2mUNI455cwFFycDFw8giHU9VAkv7 qrOQTW1XeOrlvKMrUwnnE7tN2eoiFmdvphoHLZUuKgy/ee0Gfv3dEQuR8ZYntwcGz0Bq iKwA== X-Gm-Message-State: AEkoousJcG50MZ0Rvh0o0xShTwGhRmpvaUciMZPEHNkyQlwMIicsUOqeMBHzylEwDnN4vA== X-Received: by 10.98.20.196 with SMTP id 187mr17902681pfu.0.1469491301186; Mon, 25 Jul 2016 17:01:41 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.25.212 with SMTP id 203ls3688466ioz.40.gmail; Mon, 25 Jul 2016 17:01:39 -0700 (PDT) X-Received: by 10.36.227.67 with SMTP id d64mr3354798ith.3.1469491298984; Mon, 25 Jul 2016 17:01:38 -0700 (PDT) In-Reply-To: <28358863-5be0-401a-893a-0ae5385156c2@isocpp.org> X-Original-Sender: Sean.Middleditch@gmail.com 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:27258 Archived-At: ------=_Part_1277_712424841.1469491298070 Content-Type: multipart/alternative; boundary="----=_Part_1278_2027970891.1469491298078" ------=_Part_1278_2027970891.1469491298078 Content-Type: text/plain; charset=UTF-8 Or just remove the variable i from the loop entirely because it's unused in the loop body, thus reducing the for statement to: for(; pUnicast != nullptr; pUnicat = pUnicast->Next) Not that a multi-statement increment wouldn't be useful, but this code snippet is a pretty terrible motivating example. Sorry Glenn! :) Anecdotally though (not that anyone cares, nor should you), I can't recall a time I ever felt that I needed multiple loop incrementees without eventually realizing that I was just writing my loop like an idiot. Or missing an easily-written library facility to use with for-range iterator. :) On Monday, July 25, 2016 at 8:08:23 AM UTC-7, Nicol Bolas wrote: > > > for ( int i = 0; pUnicast != NULL; > pUnicast = pUnicast->Next; i++) > { > Address address( (sockaddr_storage*) pUnicast->Address.lpSockaddr ); > > if ( !address.IsValid() ) > continue; // goto the continue block below > > if ( address.IsLoopback() ) > continue; > > if ( address.GetType() == ADDRESS_IPV6 && !address.IsGlobalUnicast() ) > continue; > > addresses[numAddresses++] = address; > > if ( numAddresses >= maxAddresses ) > break; > } > > This puts all of the iteration logic in the same place: the `for` > statement itself. So if you want to see what happens on each loop, you > don't have to look at both the top and the bottom of the `for` statement. > -- 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/8ee79066-43c5-4624-8fb5-01172eb36d29%40isocpp.org. ------=_Part_1278_2027970891.1469491298078 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Or just remove the variable i from the loop entirely becau= se it's unused in the loop body, thus reducing the for statement to:
=C2=A0 =C2=A0 for(; pUnicast !=3D nullptr; pUnicat =3D pUn= icast->Next)

Not that a multi-statement incremen= t wouldn't be useful, but this code snippet is a pretty terrible motiva= ting example. Sorry Glenn! :)

Anecdotally though (= not that anyone cares, nor should you), I can't recall a time I ever fe= lt that I needed multiple loop incrementees without eventually realizing th= at I was just writing my loop like an idiot. Or missing an easily-written l= ibrary facility to use with for-range iterator. :)

On Mo= nday, July 25, 2016 at 8:08:23 AM UTC-7, Nicol Bolas wrote:

for ( int<= /span> i =3D 0= ; pUnicast !=3D NULL<= /span>;
=C2= =A0 pUnicast =3D pUnicast->Next; i++)
{
=C2=A0 =C2=A0Address<= /span> address= ( (sockaddr_storage*) pUnicast->Address.lpSockaddr );

=C2=A0 =C2= =A0if <= /span>( !address.IsValid() <= span style=3D"color:#660">)
=C2=A0 =C2= =A0 =C2=A0 continue; // goto the continue block below
=C2=A0 =C2=A0if ( address.IsLoopback() )
=C2=A0 =C2=A0 =C2=A0 con= tinue;<= br>
=C2=A0 =C2=A0if ( address.GetType() =3D=3D ADDRESS_IPV6 &&<= /span> !address.IsGlobalUnicast() )=
=C2=A0 =C2=A0 =C2=A0 continue;

=C2=A0 =C2=A0addresses[numAddresses++] =3D address;

=C2=A0 =C2=A0if ( numAddresse= s >=3D maxAddresses )
=C2=A0 =C2=A0 =C2=A0 break<= /span>;
}

This puts all= of the iteration logic in the same place: the `for` statement itself. So i= f you want to see what happens on each loop, you don't have to look at = both the top and the bottom of the `for` statement.

--
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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/8ee79066-43c5-4624-8fb5-01172eb36d29= %40isocpp.org.
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