220 40756 article Path: news.gmane.org!.POSTED!not-for-mail From: Tony V E Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: shared_ptr and unique_ptr should both implicitly convert to observer_ptr Date: Thu, 25 Oct 2018 17:06:34 -0400 Lines: 111 Approved: news@gmane.org Message-ID: References: <81a04b52-e5cd-4543-86c5-5a0068f9647b@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="000000000000148804057913fb5c" X-Trace: blaine.gmane.org 1540501484 28547 195.159.176.226 (25 Oct 2018 21:04:44 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 25 Oct 2018 21:04:44 +0000 (UTC) To: Standard Proposals Original-X-From: std-proposals+bncBCUZ5QWKNQIORYGI3YCRUBFKLR7DE@isocpp.org Thu Oct 25 23:04:39 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ot1-f71.google.com ([209.85.210.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gFmo3-0007Ld-Di for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id r3sor5287068otb.187.2018.10.25.14.06.47 for (Google Transport Security); Thu, 25 Oct 2018 14:06:47 -0700 (PDT) Received-SPF: pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:a9d:3d1:: with SMTP id f75mr133215otf.325.1540501607318; Thu, 25 Oct 2018 14:06:47 -0700 (PDT) In-Reply-To: X-Original-Sender: tvaneerd@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=pVpbKPPv; spf=pass (google.com: domain of tvaneerd@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=tvaneerd@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:40756 Archived-At: --000000000000148804057913fb5c Content-Type: text/plain; charset="UTF-8" On Thu, Oct 25, 2018 at 4:59 PM Ville Voutilainen < ville.voutilainen@gmail.com> wrote: > On Thu, 25 Oct 2018 at 23:31, Miguel Ojeda > wrote: > > > Even if it was true I gave "zero evidence" (which it isn't), that > > doesn't mean I am being rude. However, you are being rude by stating > > publicly "you are wrong; feel free to try again", as if I had to prove > > something. No, sorry, the one making the proposal is you, so *you* are > > the one that has to prove its validity. > > Let's repeat, then: > > An optional doesn't do what observer_ptr does. The latter can > give you a null pointer when you ask its pointer value, so it can > model > "yes, I have a pointer, but it doesn't point to anything". The former > models "I may or may not have anything". > > I can always get the pointer value from an observer_ptr. I can't get a > value from an optional when it has none. > > Furthermore, > 1) I am not making a proposal. > 2) If I were, I wouldn't waste my time explaining it here. > > Also, a container of observer_ptrs would sort by the pointer value (ie address). I'm not sure how optional would sort, and if it would be sortable at all. -- Be seeing you, Tony -- 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/CAOHCbivJ%2B%2BPFDnTksQHqdQPMQWmocFuyoSzOzRxkHz0Jg-Dokw%40mail.gmail.com. --000000000000148804057913fb5c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Thu= , Oct 25, 2018 at 4:59 PM Ville Voutilainen <ville.voutilainen@gmail.com> wrote:
On Thu, 25 Oct 2018 at 23:31, Miguel Ojeda
<mi= guel.ojeda.sandonis@gmail.com> wrote:

> Even if it was true I gave "zero evidence" (which it isn'= ;t), that
> doesn't mean I am being rude. However, you are being rude by stati= ng
> publicly "you are wrong; feel free to try again", as if I ha= d to prove
> something. No, sorry, the one making the proposal is you, so *you* are=
> the one that has to prove its validity.

Let's repeat, then:

An optional<T&> doesn't do what observer_ptr<T> does. T= he latter can
give you a null pointer when you ask its pointer value, so it can
model
"yes, I have a pointer, but it doesn't point to anything". Th= e former
models "I may or may not have anything".

I can always get the pointer value from an observer_ptr. I can't get a<= br> value from an optional<T&> when it has none.

Furthermore,
1) I am not making a proposal.
2) If I were, I wouldn't waste my time explaining it here.


Also, a container of observer_ptrs wou= ld sort by the pointer value (ie address).
I'm not sure how o= ptional<T&> would sort, and if it would be sortable at all.


--
Be seeing y= ou,
Tony

--
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