220 25596 <20160420054934.GA31261@noemi.bahnhof.se> article Path: news.gmane.org!not-for-mail From: Magnus Fromreide Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Linked std::table / std::matrix proposal Date: Wed, 20 Apr 2016 07:49:34 +0200 Lines: 69 Approved: news@gmane.org Message-ID: <20160420054934.GA31261@noemi.bahnhof.se> References: <20160416005425.4902992.3247.9842@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1461131386 2817 80.91.229.3 (20 Apr 2016 05:49:46 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 20 Apr 2016 05:49:46 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDELLREETMBRB4FQ3S4AKGQEJ3YOGEQ@isocpp.org Wed Apr 20 07:49:40 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f197.google.com ([209.85.217.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1asl18-00063K-Dh for gclcip-std-proposals@m.gmane.org; Wed, 20 Apr 2016 07:49:38 +0200 Original-Received: by mail-lb0-f197.google.com with SMTP id f14sf3434793lbb.2 for ; Tue, 19 Apr 2016 22:49:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to:user-agent :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=O3FToLEJJxh6B9wh+PGm+hXddA8hFY/N6Oo5zmo4BIw=; b=JeygAWi8hevvPp/xUnKp0JMRP2p8z5hZQbBFytrfvqLagWPeK27YF11ZNTBmpDHHNt 8EfRPRUIoHCBqjB/IBHj9lbw7SI+MmebLGOVpOekH5Fd/UgXdRv7v6Bsaf7wy2JgE7ru /3LDhhcoo5DK+VBy5Xgn/kI4wCVtThyT7AkG6hPV/YEtcPvV1J4LeOtBGf4sneN3Rps4 a3iunbrgzrHwowAWF2CmsfWwpR+Nmq3issJNh32b+C9sI7ugSv/9mIBocM+UXM6XRdK5 KRDve8M7zOfRypf7cZnUEuij5YRSj3uhPjNMWinEnYGccaltzldd5hjwBukjBYY 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:subject:message-id:mail-followup-to :references:mime-version:content-disposition:in-reply-to:user-agent :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=O3FToLEJJxh6B9wh+PGm+hXddA8hFY/N6Oo5zmo4BIw=; b=ecLWfiR0gVpyzDE+2atZXrYgfRZ9U2txDd6osYrp61jr4L/O8sbq8W/Ld4RpkVu0rD Yy1DLj07iVxJnxR2KK6qArZDAbdBq92od1/9YwHVZExLT6Wkvt9QMUqs4eB1PEOXbvgR +lGAK0+VG5ELkd7auTaBOv6rVvEUMrigS7spW8o9nsscq/QLGdvH7cTjyhJbAMY7EKvz wGSD6ERyr7JGejFD/jOJpjVYr7hCmf/0RKhPYln4aj9yBEzJ8+dyNnyfNS6wHHTGhLQM 4OeZLLaefNcXeZ5Rl4jzH2akAcUKc91t3WWpl88lbMyzsTjVhJdIawcrBCm X-Gm-Message-State: AOPr4FXpAzmt5R+E3HMtNRxZ1Z2ZvPo2Svc/1VbZo4NMPOBi4Q1EYdsUwsVo5ZVQE0eIgw== X-Received: by 10.25.15.68 with SMTP id e65mr709524lfi.8.1461131377850; Tue, 19 Apr 2016 22:49:37 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.16.93 with SMTP id f90ls599524lfi.89.gmail; Tue, 19 Apr 2016 22:49:36 -0700 (PDT) X-Received: by 10.25.151.72 with SMTP id z69mr2849030lfd.0.1461131376132; Tue, 19 Apr 2016 22:49:36 -0700 (PDT) Original-Received: from mail.lysator.liu.se (mail.lysator.liu.se. [2001:6b0:17:f0a0::3]) by mx.google.com with ESMTPS id r78si2361794lfg.122.2016.04.19.22.49.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Apr 2016 22:49:36 -0700 (PDT) Received-SPF: pass (google.com: domain of magfr@lysator.liu.se designates 2001:6b0:17:f0a0::3 as permitted sender) client-ip=2001:6b0:17:f0a0::3; Original-Received: from mail.lysator.liu.se (localhost [127.0.0.1]) by mail.lysator.liu.se (Postfix) with ESMTP id C8E704001C for ; Wed, 20 Apr 2016 07:49:35 +0200 (CEST) Original-Received: from noemi.bahnhof.se (h-176-10-249-241.na.cust.bahnhof.se [176.10.249.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.lysator.liu.se (Postfix) with ESMTPSA id A2D1540012 for ; Wed, 20 Apr 2016 07:49:35 +0200 (CEST) Mail-Followup-To: std-proposals@isocpp.org Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Virus-Scanned: ClamAV using ClamSMTP X-Original-Sender: magfr@lysator.liu.se X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of magfr@lysator.liu.se designates 2001:6b0:17:f0a0::3 as permitted sender) smtp.mailfrom=magfr@lysator.liu.se 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:25596 Archived-At: On Tue, Apr 19, 2016 at 08:21:55PM -0400, Tony V E wrote: > On Sat, Apr 16, 2016 at 1:06 PM, Michael Allwright > wrote: > > > > > I'm not exactly sure what you mean by ruling out vector-of-vector > > implementations, I'm suggesting adding a new container to the standard, not > > removing anything. The vector-of-vectors approach is certainly ok for > > situations where the layout and dimensions of the table/matrix are > > relatively fixed, but in the case where we need to add/remove/shift columns > > and rows, the code to do this can be quite unsafe and bloated. > > > > > When you define a container for the standard, you don't define how it is > implemented, you only define how it looks from the outside - its API. You > _somewhat_ limit how it might be implemented by providing certain > guarantees - ie > > - do iterators get invalided when adding/removing (for examples in STL: > vector yes, list no) > - what is the O(n) time for inserting, removing, etc, > - are the iterators ForwardIterators, BidirectionalIterators, or > RandomAccessIterators, etc > - etc I could not agree more with this and would vey much see this added as a FAQ or something to the group. > > This container doesn't aim to solve problems such as implementing large > > databases or solving large sets of simultaneous equations through matrix > > operations, boost already has some quite sophisticated solutions for this. > > The aim of this container is to provide programmers with a tool to safely > > manipulate small to medium sets of data that is organised as rows and > > columns. > > > > > So this is exactly what we need to focus on - what is the aim, and was is > NOT the aim. (Like you say, NOT solving equations, etc). > > So we need to decide what trade-offs to make - which operations should be > fast, which don't matter - do we expect users to traverse more, or > insert/remove more? Do they want to hold iterators, then insert/remove, > then continue to use those old iterators expecting them to still point to > where they previously did? > > P.S. I specifically bring up vector of vector, because it will, in many > cases, probably be faster than a node-based container - even when doing > significant inserts etc. Vectors keep data local in memory (ie keep cache > lines happy), node-based containers spread the data out across memory. And > allocation is slow (and typically requires a lock for thread safety). So > allocating a single node vs moving a bunch of data over in a vector... > vector often wins. Here I have to say that I think the implementation using a vector with striding iterators should be considered as well - given that the container is small it might end up beeing faster than both vector-of-vectors and linked webs. This also have the advantage that the whole thing becomes an new adaptor rather than a new container so you could put it on top of any random- iterable container. /MF -- 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/20160420054934.GA31261%40noemi.bahnhof.se. .