220 25843 <09bfdbe7-70d9-4d25-9f51-4b79cecfb79f@isocpp.org> article Path: news.gmane.org!not-for-mail From: Morwenn Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Fixed-size views and spans Date: Sun, 8 May 2016 02:44:58 -0700 (PDT) Lines: 85 Approved: news@gmane.org Message-ID: <09bfdbe7-70d9-4d25-9f51-4b79cecfb79f@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2087_973212256.1462700698492" X-Trace: ger.gmane.org 1462700749 18211 80.91.229.3 (8 May 2016 09:45:49 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 8 May 2016 09:45:49 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC2ZP4V74IFBBHEVXS4QKGQEIDYYRLA@isocpp.org Sun May 08 11:45:42 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f199.google.com ([209.85.214.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1azLGp-0004cr-6v for gclcip-std-proposals@m.gmane.org; Sun, 08 May 2016 11:45:03 +0200 Original-Received: by mail-ob0-f199.google.com with SMTP id je7sf329544233obb.0 for ; Sun, 08 May 2016 02:45:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=r5SHIKekdrFjBamz8muTuqv54f2mEznmj5pd3b624hg=; b=EaW5+191ufMN0mZ6HLWYgbhw4+Vbxmu+4zaP9tN9cAufE8gAOi3duUfT8qW5XA2aov rWBXsuh1BirOFaIGGR4blBqrUuvmUpDeP9uf5dWLxclpof8Hi/Br0650YR9PtYwNtGKm 2tJkE5256Uoz2onWKd7HA3LuLeUSlHaZsajJpcw1OeEJf3cvLS6nKOnOW2f3TDEQvcTA tC/AmVVJ5kKwW2W/hqk8B+EBKO+nU1HQprbbgMj6uCednjo8RnhHEBJkxZyyGBWGPbsQ R+bxsE+9Snwx8JGCa63mzyrDwDalK9hThMa3a4veNWyEhrdMHP1eKeggaMe8/9oGDBm/ T0Jw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=r5SHIKekdrFjBamz8muTuqv54f2mEznmj5pd3b624hg=; b=b2FGq6NE9xVzN+S8qdhsMl95dtWwh+UW0TzncCBd5qGw70YG5J504R42HOT+QQE2OZ RMud+Mqr/Tr2SB09t7YXk/+L5hi5COkxQse7xYxCtf8+Cer8jYtKoMsjf8quAzTqESWR tuaWKC6XGH2/swqki5H2cEsmKxqDNcHxjeeV3sVrf6Owje1/FkZLZ0I5HPZU/3a3WwNL 2Luoo99wcg8PgEqlEC/B+09hMEccaq5lfAa5bPTUV3OdbHPBaF0UwnPcVRfLsuRGWp9P hj6gYAD4P5sA6Nks1B9A2Fllz3/Juv3ZHTgvDUPxmw6ZquEk/mCgLoFzHtHWooFaGzNs Sfrw== 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:message-id:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=r5SHIKekdrFjBamz8muTuqv54f2mEznmj5pd3b624hg=; b=YkbhfZFrVE6fdX5ILTMJbRZNwVF7rrI5/k0+uJSB0Y+6waRoBj1WHifdf2o/aGsANY ZW5u6KOG8ROOrq1+G7mXhy2zmyBMpwhzjmU/BYHTbAjgKlxviA4kAb6HYcH8d+6fMbxy gHSxrNdwTq5Zp+WdYb4ghIHLifU0xN43nROPs1xGyAt5msJ6kIkE0d4DZH4FUy+5IrJV axqWNpOr5jqlmcdBJttxke9QuWitik8TO3UHtKtmqem+i5kn3p/RSaAovSoyjPmbwxbT EXFwkdsHteb4Je3qTF+tmsfBmrleOvnCZh1o4TG1Jii9h1NxFe2NzSFRGrxm3adTBp41 OFLw== X-Gm-Message-State: AOPr4FXco2nLy8rJkVkGkhEICeB+w8VJ8qLz9UFUXtOK9UUX31FZaZ34lX/OC5QN8Z8HcA== X-Received: by 10.107.135.214 with SMTP id r83mr18820737ioi.19.1462700701993; Sun, 08 May 2016 02:45:01 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.15.103 with SMTP id x100ls1720397ioi.54.gmail; Sun, 08 May 2016 02:45:00 -0700 (PDT) X-Received: by 10.36.79.141 with SMTP id c135mr696itb.10.1462700700215; Sun, 08 May 2016 02:45:00 -0700 (PDT) X-Original-Sender: morwenn29@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:25843 Archived-At: ------=_Part_2087_973212256.1462700698492 Content-Type: multipart/alternative; boundary="----=_Part_2088_2045467701.1462700698492" ------=_Part_2088_2045467701.1462700698492 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Another quick idea: sometimes we know that we will perform an operation on= =20 the next N element of an iterable, where N is known at compile-time. It=20 might be the case for what we could call =C2=AB bottom-up divide-and-conque= r =C2=BB=20 algorithms. For example, WikiSort=20 starts by dividing the=20 collection to sort in chunks of 8 elements and sorting them before=20 proceeding with soe smart merging operations. We know how to speed up some= =20 operations when the number of elements is small and known at compile-time:= =20 sorting networks are an excellent tool to sort integers when the size of=20 the collection to sort is known at compile-time. However there is no simple way to tell to the standard library's algorithms= =20 that they will work with a small number of elements known at compile-time.= =20 A solution would be to add span and view classes that take an integer=20 template parameter for their size, and let library implementers add=20 overloads to algorithms for such utility classes when they think it is=20 useful (it could still fit the Ranges TS design). Any thoughts about the usefulness of such fixed-size span and view classes? --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/09bfdbe7-70d9-4d25-9f51-4b79cecfb79f%40isocpp.or= g. ------=_Part_2088_2045467701.1462700698492 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Another quick idea: sometimes we know that we will perform= an operation on the next N element of an iterable, where N is known at com= pile-time. It might be the case for what we could call =C2=AB bottom-up div= ide-and-conquer =C2=BB algorithms. For example, WikiSort starts by dividing the collectio= n to sort in chunks of 8 elements and sorting them before proceeding with s= oe smart merging operations. We know how to speed up some operations when t= he number of elements is small and known at compile-time: sorting networks = are an excellent tool to sort integers when the size of the collection to s= ort is known at compile-time.

However there is no simple way to tell= to the standard library's algorithms that they will work with a small = number of elements known at compile-time. A solution would be to add span a= nd view classes that take an integer template parameter for their size, and= let library implementers add overloads to algorithms for such utility clas= ses when they think it is useful (it could still fit the Ranges TS design).=

Any thoughts about the usefulness of such fixed-size span and view = classes?

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To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/09bfdbe7-70d9-4d25-9f51-4b79cecfb79f= %40isocpp.org.
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