220 2302 <894320fe-ed2c-4239-a3a7-e1b9aaa3b95e@isocpp.org> article
Path: news.gmane.org!not-for-mail
From: Nicol Bolas <jmckesson@gmail.com>
Newsgroups: gmane.comp.lang.c++.isocpp.proposals
Subject: Re: optional<T>, one more value or two states
Date: Sat, 26 Jan 2013 05:29:55 -0800 (PST)
Lines: 80
Approved: news@gmane.org
Message-ID: <894320fe-ed2c-4239-a3a7-e1b9aaa3b95e@isocpp.org>
References: <CAGsORuC1ADLXgS9AZZiTo=knmhT-+9Yj+82v+b8Nq_WJpb1fOg@mail.gmail.com>
 <CAFk2RUZyZA0LLUNuVNcnibv+qBF69jMytWQL3tkp-Kp21oEU+A@mail.gmail.com>
 <CAGsORuB-Qkx-LaXj2jO4yLrwN524kiJONSg7oczkQZHYaJ6ASg@mail.gmail.com>
 <d360a952-28ae-4d57-bb20-96fd08725a0b@isocpp.org>
 <CAPXezF_JggyMaXjGS9r1EAGVu1NhQBEyGEXB8tKmVqgFfjoCeg@mail.gmail.com>
 <CALJmx62zJd_tZ=XYL7TaSkRN6432SObwH9YS87eLX-h_pMuFYQ@mail.gmail.com>
 <CAOHCbivAK0ypmMhrhJ3zKpF8BHu3h_rUNzeao-HnibJkC-qqGw@mail.gmail.com>
 <ef15483d-5665-4da3-9b79-aefd3c725e1b@isocpp.org>
 <CAOHCbithEUfm+w_06V71=hpkqGUJvqiyDFqD7fesfgLy4uUieg@mail.gmail.com>
 <2c2b9360-8e5e-422d-9b85-124bd947b004@isocpp.org>
 <CAOHCbivJzdQbe22URgRuahCYYDPG8Ygsc4VG7f61zRBWXogekg@mail.gmail.com>
 <4f505b21-669a-4ef0-95b9-edf9e5afa22d@isocpp.org>
 <f0c3cd2a-f285-4a36-b33f-3a7ddcb5ba89@isocpp.org>
Reply-To: std-proposals@isocpp.org
NNTP-Posting-Host: plane.gmane.org
Mime-Version: 1.0
Content-Type: multipart/alternative; 
	boundary="----=_Part_796_16203720.1359206995428"
X-Trace: ger.gmane.org 1359207002 16254 80.91.229.3 (26 Jan 2013 13:30:02 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Sat, 26 Jan 2013 13:30:02 +0000 (UTC)
To: std-proposals@isocpp.org
Original-X-From: std-proposals+bncBCEKFTV6ZUMBBVNUR6EAKGQED5WUDHA@isocpp.org Sat Jan 26 14:30:22 2013
Return-path: <std-proposals+bncBCEKFTV6ZUMBBVNUR6EAKGQED5WUDHA@isocpp.org>
Envelope-to: gclcip-std-proposals@m.gmane.org
Original-Received: from mail-oa0-f71.google.com ([209.85.219.71])
	by plane.gmane.org with esmtp (Exim 4.69)
	(envelope-from <std-proposals+bncBCEKFTV6ZUMBBVNUR6EAKGQED5WUDHA@isocpp.org>)
	id 1Tz5po-0002HG-8C
	for gclcip-std-proposals@m.gmane.org; Sat, 26 Jan 2013 14:30:16 +0100
Original-Received: by mail-oa0-f71.google.com with SMTP id n12sf8294955oag.6
        for <gclcip-std-proposals@m.gmane.org>; Sat, 26 Jan 2013 05:29:58 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=x-received:x-beenthere:x-received:date:from:to:message-id
         :in-reply-to:references:subject:mime-version:x-original-sender
         :reply-to:precedence:mailing-list:list-id:x-google-group-id
         :list-post:list-help:list-archive:list-subscribe:list-unsubscribe
         :content-type;
        bh=L1ICt8NSbH19WtdEJ0hYPnDhHD9CvI/o9cx4Y/xreyc=;
        b=az6V+FQSgKsERsxna4rP0gcrqs6kxdYvCdsBJJuEpi8Hd7Y6ENKN9v320PwpILHkZo
         eyqT/zfVPL365Qx5iluGKJG4PsYyNANApJ2E0cq+3DvlrDzUYL9KZ0AWMWyjfm52EEXC
         iCpEYLl9CbUhWyIO+zrMcoAXWDIpXvCcigmx+Xuj94HmJwVAEOymkvblh7HZvcSmONuz
         dMzFLLc3/sqQvdV7heX349iKVyJyyAg0tz/GJmJkIzq46w15qe6Sh09gJm5r+R9ytjYv
         XGxWIxmLVf9i+/vDFztCEGsIx/dpvPZ/5M02l91GutXEcTWrBmBqIQvveHQWPup5h0If
         68aw==
X-Received: by 10.42.123.66 with SMTP id q2mr6217991icr.15.1359206997803;
        Sat, 26 Jan 2013 05:29:57 -0800 (PST)
X-BeenThere: std-proposals@isocpp.org
Original-Received: by 10.50.242.6 with SMTP id wm6ls314746igc.20.canary; Sat, 26 Jan
 2013 05:29:57 -0800 (PST)
X-Received: by 10.50.5.174 with SMTP id t14mr335455igt.11.1359206996986;
        Sat, 26 Jan 2013 05:29:56 -0800 (PST)
In-Reply-To: <f0c3cd2a-f285-4a36-b33f-3a7ddcb5ba89@isocpp.org>
X-Original-Sender: jmckesson@gmail.com
Precedence: list
Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org
List-ID: <std-proposals.isocpp.org>
X-Google-Group-Id: 399137483710
List-Post: <http://groups.google.com/a/isocpp.org/group/std-proposals/post?hl=en>,
 <mailto:std-proposals@isocpp.org>
List-Help: <http://support.google.com/a/isocpp.org/bin/topic.py?hl=en&topic=25838>,
 <mailto:std-proposals+help@isocpp.org>
List-Archive: <http://groups.google.com/a/isocpp.org/group/std-proposals/?hl=en>
List-Subscribe: <http://groups.google.com/a/isocpp.org/group/std-proposals/subscribe?hl=en>,
 <mailto:std-proposals+subscribe@isocpp.org>
List-Unsubscribe: <http://groups.google.com/a/isocpp.org/group/std-proposals/subscribe?hl=en>,
 <mailto:googlegroups-manage+399137483710+unsubscribe@googlegroups.com>
Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:2302
Archived-At: <http://permalink.gmane.org/gmane.comp.lang.c++.isocpp.proposals/2302>

------=_Part_796_16203720.1359206995428
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable



On Saturday, January 26, 2013 4:44:25 AM UTC-8, R=C3=B3bert D=C3=A1vid wrot=
e:
>
>
>
> 2013. janu=C3=A1r 26., szombat 0:22:11 UTC+1 id=C5=91pontban Nicol Bolas =
a=20
> k=C3=B6vetkez=C5=91t =C3=ADrta:
>>
>> Yes: `optional<T*>` exists. Such an object has 3 possible states: the=20
>> optional could be empty. The optional could contain a valid pointer. Or =
the=20
>> optional could contain *nullptr*.
>>
>>
> I'd argue that this is still two state: empty, or a valid pointer. nullpt=
r=20
> *is *a valid pointer value, or to be more exact, T*(nullptr) is.
>

This is exactly my point: that's why you can't have use "null" to mean=20
"empty optional." Because it might mean something else.

--=20

---=20
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 e=
mail 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-proposa=
ls/?hl=3Den.



------=_Part_796_16203720.1359206995428
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<br><br>On Saturday, January 26, 2013 4:44:25 AM UTC-8, R=C3=B3bert D=C3=A1=
vid wrote:<blockquote class=3D"gmail_quote" style=3D"margin: 0;margin-left:=
 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><br><br>2013. janu=
=C3=A1r 26., szombat 0:22:11 UTC+1 id=C5=91pontban Nicol Bolas a k=C3=B6vet=
kez=C5=91t =C3=ADrta:<blockquote class=3D"gmail_quote" style=3D"margin:0;ma=
rgin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex">Yes: `optional=
&lt;T*&gt;` exists. Such an object has 3 possible states: the optional coul=
d be empty. The optional could contain a valid pointer. Or the optional cou=
ld contain <i>nullptr</i>.<br><div><br></div></blockquote><div><br>I'd argu=
e that this is still two state: empty, or a valid pointer. <span style=3D"f=
ont-family:courier new,monospace">nullptr</span> <b><i>is </i></b>a valid p=
ointer value, or to be more exact, <span style=3D"font-family:courier new,m=
onospace">T*(nullptr)</span> is.<br></div></blockquote><div><br>This is exa=
ctly my point: that's why you can't have use "null" to mean "empty optional=
.." Because it might mean something else.<br></div>

<p></p>

-- <br />
&nbsp;<br />
--- <br />
You received this message because you are subscribed to the Google Groups &=
quot;ISO C++ Standard - Future Proposals&quot; group.<br />
To unsubscribe from this group and stop receiving emails from it, send an e=
mail to std-proposals+unsubscribe@isocpp.org.<br />
To post to this group, send email to std-proposals@isocpp.org.<br />
Visit this group at <a href=3D"http://groups.google.com/a/isocpp.org/group/=
std-proposals/?hl=3Den">http://groups.google.com/a/isocpp.org/group/std-pro=
posals/?hl=3Den</a>.<br />
&nbsp;<br />
&nbsp;<br />

------=_Part_796_16203720.1359206995428--

.