220 6202 article Path: news.gmane.org!not-for-mail From: Richard Smith Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Specialization of std::stack for std::forward_list Date: Fri, 6 Sep 2013 17:14:38 -0700 Lines: 206 Approved: news@gmane.org Message-ID: References: <5b046beb-f0c0-4cd2-96bb-bc7007da13e9@isocpp.org> <1111d35d-1a91-47b3-a2a4-01c2b91a6527@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7bf0f67a70d88d04e5c00aa5 X-Trace: ger.gmane.org 1378512879 10564 80.91.229.3 (7 Sep 2013 00:14:39 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 7 Sep 2013 00:14:39 +0000 (UTC) Cc: inkwizytoryankes@gmail.com To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDVNBJG4YAIBB3W7VGIQKGQEKOVRIII@isocpp.org Sat Sep 07 02:14:40 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qa0-f70.google.com ([209.85.216.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VI6Ai-0003KB-Db for gclcip-std-proposals@m.gmane.org; Sat, 07 Sep 2013 02:14:40 +0200 Original-Received: by mail-qa0-f70.google.com with SMTP id ii20sf1918671qab.1 for ; Fri, 06 Sep 2013 17:14:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe:content-type; bh=+0an8m5kLf7kuaVilyKtd5z/7nCnK/lUk/nbE/KfGyM=; b=WBCKCkVHXBhpOb1CSFgTqGV7o4PNmjSvaBOB9uGxT5Ddmj9OOfpmvOhAM41ia5vECe 2o+zivwECsQfvDtBWstda/V0my9ZHUyL/Uhw8O6zDEYxrXVn9SvoR0biR0QChFkdvour zrlMVSuV7QpfQVub7xYoMDoLNTrtNbEUUGDH7z0QPuXReyv0qlZYjO8b2ipPhApWwQYx Wbj/ZryBKl/5mAzOhdSCCY1R+OWBC3jgZOk+BL+TAzflUX1Ax+XN6plL99BQMwihJFKp ca+q7VGoNEq8+uszhRszo3zxgfU0Gl3QRyXbYHbf1jZn9HstuaNyhKuaIu6a25CEyv2T RjFg== X-Received: by 10.236.7.130 with SMTP id 2mr1750962yhp.4.1378512879542; Fri, 06 Sep 2013 17:14:39 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.5.9 with SMTP id o9ls362010qeo.49.gmail; Fri, 06 Sep 2013 17:14:38 -0700 (PDT) X-Received: by 10.58.127.202 with SMTP id ni10mr412729veb.27.1378512878748; Fri, 06 Sep 2013 17:14:38 -0700 (PDT) Original-Received: from mail-ve0-x235.google.com (mail-ve0-x235.google.com [2607:f8b0:400c:c01::235]) by mx.google.com with ESMTPS id ed9si120761vcb.6.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 06 Sep 2013 17:14:38 -0700 (PDT) Received-SPF: pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c01::235 as permitted sender) client-ip=2607:f8b0:400c:c01::235; Original-Received: by mail-ve0-f181.google.com with SMTP id oy12so2141475veb.12 for ; Fri, 06 Sep 2013 17:14:38 -0700 (PDT) X-Received: by 10.220.181.136 with SMTP id by8mr4917134vcb.11.1378512878489; Fri, 06 Sep 2013 17:14:38 -0700 (PDT) Original-Sender: metafoo@gmail.com Original-Received: by 10.58.98.1 with HTTP; Fri, 6 Sep 2013 17:14:38 -0700 (PDT) In-Reply-To: <1111d35d-1a91-47b3-a2a4-01c2b91a6527@isocpp.org> X-Original-Sender: richard@metafoo.co.uk X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c01::235 as permitted sender) smtp.mail=metafoo@gmail.com; dkim=pass header.i=@gmail.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:6202 Archived-At: --047d7bf0f67a70d88d04e5c00aa5 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: quoted-printable On Fri, Sep 6, 2013 at 4:48 PM, Vlad from Moscow wrote= : > I doi not agree that we need a new version of stack. All what we need we > already have. Moreover stack does not require member function size(). It = is > unnecessary function. What is size()? Inf act is is an analogy of an > iterator. Consider using size with an array something as > > for ( int i =3D 0; i < n; i++ ) a[i] =3D i; > > a + 0 and a + n give us iterators. However stack has no iterators so it > does not need the size() function. The logic of functionality of the stac= k > is simple. We are popping out elements of the stack while it is not empty= .. > > What we need is simply a specialization of std::stack for > std::forward_list. std::forward_list has all functionality of the stack. > We risk introducing surprising behavior if we add support for this. Right now, std::stack::push adds elements to the *end* of the stack, and this is an observable property in various ways (for instance, due to the container member being protected rather than private). Consider: template struct Container> struct MyStack : public std::stack> { using stack::stack; void print() { for (int n : this->c) std::cout << n << std::endl; } }; If we taught std::stack to switch to using push_front instead of push_back when its container is a std::forward_list, MyStack::print would print in the opposite order from MyStack::print. This seems a bit too reminiscent of std::vector for comfort. =D3=D5=C2=C2=CF=D4=C1, 7 =D3=C5=CE=D4=D1=C2=D2=D1 2013 =C7., 3:14:13 UTC+4 = =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=D8 > inkwizyt...@gmail.com =CE=C1=D0=C9=D3=C1=CC: > >> >> >> On Friday, September 6, 2013 7:37:38 PM UTC+2, Vlad from Moscow wrote: >>> >>> I would like to propose to include specialization of std::stack for >>> std::forward_list. >>> >>> In fact std::forward_list has already all characteristics of a stack. >>> There will be only one difference compared with the primary class >>> std::stack: the specialization will not contain member function size() >>> because std::forward_list has no such member. >>> >>> What will you say? >>> >> >> why no `size()`? nobody can access inner list ergo stack can easy >> determine size in const time. `std::stack` require only: >> >> back >> push_back >> pop_back >> >> that can be in case `std::forward_list` inverted to: >> >> front >> push_front >> pop_front >> >> maybe we need simple new version of stack? `std::stack_front`? >> >> >> >> -- > > --- > 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/. > --=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/. --047d7bf0f67a70d88d04e5c00aa5 Content-Type: text/html; charset=KOI8-R Content-Transfer-Encoding: quoted-printable
On Fri, Sep 6, 2013 at 4:48 PM, Vlad from Moscow <vlad.= moscow@mail.ru> wrote:
I doi not agree that w= e need a new version of stack. All what we need we already have. Moreover s= tack does not require member function size(). It is unnecessary function. W= hat is size()? Inf act is is an analogy of an iterator. Consider using size= with an array something as
=9A
for ( int i =3D 0; i < n; i++ ) a[i] =3D i;
=9A
a + 0 and a + n give us iterators. However stack has no iter= ators so it does not need the size() function. The logic of functionality o= f the stack is simple. We are popping out elements of the stack while it is= not empty.
=9A
What we need is simply a specialization of std::stack fo= r std::forward_list. std::forward_list has all functionality of the stack.<= /div>

We risk introducing surprising = behavior if we add support for this. Right now, std::stack::push adds eleme= nts to the *end* of the stack, and this is an observable property in variou= s ways (for instance, due to the container member being protected rather th= an private). Consider:

template<template<typename...> struct Containe= r>
struct MyStack : public std::stack<int, Container<int= >> {
=9A using stack::stack;
=9A void print() {
=9A =9A for (int n : this->c)
=9A =9A =9A std::cout <&= lt; n << std::endl;
=9A }
};

If we taught std::stack to switch to using push_front instead of p= ush_back when its container is a std::forward_list, MyStack<std::forward= _list>::print would print in the opposite order from MyStack<any_othe= r_container>::print.

This seems a bit too reminiscent of std::vector<bool= > for comfort.

=D3=D5=C2=C2=CF=D4=C1, 7 =D3=C5=CE=D4=D1=C2=D2=D1 2013=9A=C7., 3:14:13= UTC+4 =D0=CF=CC=D8=DA=CF=D7=C1=D4=C5=CC=D8 inkwizyt...@gmail.com =CE=C1=D0=C9=D3=C1=CC= :


On Friday, September 6, 2013 7:37:38 PM UTC+2, Vla= d from Moscow wrote:
I would like to propose to include specialization of = std::stack for std::forward_list.
=9A
In fact std::for= ward_list has already all characteristics of a stack. There will be only on= e difference compared with the primary class std::stack:=9A the specializat= ion will not contain member function size() because std::forward_list has n= o such member.
=9A
What will you say?
=9A
why no `size()`? n= obody can access inner list ergo stack can easy determine size in const tim= e. `std::stack` require only:

back
push_back
pop_back

that can be in case `std::forward_= list` inverted to:

front
push_front
pop_front

maybe we = need simple new version of stack? `std::stack_front`?

=



<= div class=3D"h5">

--
=9A
---
You received this message because you are subscribed to the Google Groups &= quot;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/gro= up/std-proposals/.

--
 
---
You received this message because you are subscribed to the Google Groups &= quot;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-proposals/<= /a>.
--047d7bf0f67a70d88d04e5c00aa5-- .