220 37293 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicolas Lesser Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Pointer overload for || Date: Sun, 11 Mar 2018 11:00:38 +0100 Lines: 131 Approved: news@gmane.org Message-ID: References: <1fea07df-46a6-4df2-865a-849be8f8d129@isocpp.org> <05da71c2-80cf-63dd-b2c6-8cd342db5140@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="089e08e5c2e9f08919056720183d" X-Trace: blaine.gmane.org 1520762319 30364 195.159.176.226 (11 Mar 2018 09:58:39 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 11 Mar 2018 09:58:39 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDXKNLEUTADRBR74SPKQKGQEW747PHY@isocpp.org Sun Mar 11 10:58:35 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f70.google.com ([209.85.218.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1euxkQ-0007mo-CY for gclcip-std-proposals@m.gmane.org; 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[209.85.220.65]) by mx.google.com with SMTPS id h12sor1957024oti.158.2018.03.11.03.00.39 for (Google Transport Security); Sun, 11 Mar 2018 03:00:39 -0700 (PDT) Received-SPF: pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; X-Received: by 10.157.75.130 with SMTP id k2mr3074273otf.244.1520762438583; Sun, 11 Mar 2018 03:00:38 -0700 (PDT) Original-Received: by 2002:a9d:5e01:0:0:0:0:0 with HTTP; Sun, 11 Mar 2018 03:00:38 -0700 (PDT) Original-Received: by 2002:a9d:5e01:0:0:0:0:0 with HTTP; Sun, 11 Mar 2018 03:00:38 -0700 (PDT) In-Reply-To: <05da71c2-80cf-63dd-b2c6-8cd342db5140@gmail.com> X-Original-Sender: blitzrakete@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=ogR4gWjo; spf=pass (google.com: domain of blitzrakete@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=blitzrakete@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=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:37293 Archived-At: --089e08e5c2e9f08919056720183d Content-Type: text/plain; charset="UTF-8" > Also that inverted logic has a high chance of confusing anyone who comes > across it, and it some cases, it is not even clear which or operator you > choose. > > var = var || allocate(); > > If allocate doesn't return a pointer, but a boolean (or due to a refactor > it changes) then the expression above would no longer do the right thing: > assign 1 to var if either expression is true, which is not expected. I don't know precisely what you mean by "inverted" logic My bad, that's not true. I was thinking of &&. , but I don't agree that it would necessarily confuse anyone who comes across it - it would just be unfamiliar syntax, which they would look up. It's true that the expression would compile regardless of whether allocate() returns a bool or a pointer, which could cause a surprising bug due to implicit pointer-to-bool conversion, but I don't feel like that's very likely, or that it would be very likely that a refactor would cause a problem there either. Specifically if your allocate() is changed from returning a pointer to returning a bool during a refactor, its signature would change in other ways that would cause a compile error there, i.e. taking a reference to the pointer to allocate as an argument instead of returning it. That is true, my example was pretty bad. Jefferson Carpenter -- 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/is ocpp.org/d/msgid/std-proposals/05da71c2-80cf-63dd-b2c6- 8cd342db5140%40gmail.com. -- 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/CALmDwq1SROgxcm8%3D7q2WaC%3DF4-cfkUycvEC6oCroEna-KFDZ8Q%40mail.gmail.com. --089e08e5c2e9f08919056720183d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

> Also that inverted logic has a high chance of confusing anyone who com= es
> across it, and it some cases, it is not even clear which or operator y= ou
> choose.
>
> var =3D var || allocate();
>
> If allocate doesn't return a pointer, but a boolean (or due to a r= efactor
> it changes) then the expression above would no longer do the right thi= ng:
> assign 1 to var if either expression is true, which is not expected.
I don't know precisely what you mean by "inverted" logic

My bad, t= hat's not true. I was thinking of &&.
=
, but I don't agree that it would necessarily = confuse anyone who comes across it - it would just be unfamiliar syntax, wh= ich they would look up.=C2=A0 It's true that the expression would compi= le regardless of whether allocate() returns a bool or a pointer, which coul= d cause a surprising bug due to implicit pointer-to-bool conversion, but I = don't feel like that's very likely, or that it would be very likely= that a refactor would cause a problem there either.=C2=A0 Specifically if = your allocate() is changed from returning a pointer to returning a bool dur= ing a refactor, its signature would change in other ways that would cause a= compile error there, i.e. taking a reference to the pointer to allocate as= an argument instead of returning it.

That is true, my example was pretty bad.


Jefferson Carpenter

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