220 33840 <51add97a-3379-4b9e-9bd3-8972ed0e7636@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: string_view for fstream::open() Date: Fri, 11 Aug 2017 12:09:18 -0700 (PDT) Lines: 99 Approved: news@gmane.org Message-ID: <51add97a-3379-4b9e-9bd3-8972ed0e7636@isocpp.org> References: <3456831.gsseCm4DuK@tjmaciei-mobl1> <6240d6af-a518-4788-a56f-b7d0c8976dc4@isocpp.org> <250415405.SNDfSfLC7e@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2226_1153724885.1502478558852" X-Trace: blaine.gmane.org 1502478562 2608 195.159.176.226 (11 Aug 2017 19:09:22 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 11 Aug 2017 19:09:22 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBX4BXDGAKGQECKXQ6TA@isocpp.org Fri Aug 11 21:09:18 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f71.google.com ([209.85.213.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dgFJ4-0000GO-Re for gclcip-std-proposals@m.gmane.org; Fri, 11 Aug 2017 21:09:14 +0200 Original-Received: by mail-vk0-f71.google.com with SMTP id u200sf17213100vkd.1 for ; Fri, 11 Aug 2017 12:09:21 -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:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=kwKSbhTwe1sURT7PthXxteRn0w1xOxJogQ6ibhTwmw4=; b=XPUJidhZOiMMFYEPKT/ISPzhStdoYqV9exRrUQZaqbDU1DEJDjRd3gbX2C1xslrVVF UHcI9O4zPU8+UGZiEbcJPWvisb5VtKtgpRGOU2+t0ufB4TW3ekTIaVB43ezJjTPkrhC1 8lzfBFd6U7BtPq9eSzXuWMepzc9oawBjDRFA8byoyKVv8zuvxEBjiV3ntbvqG3Wob6ro 5DE814ZKXVSlj2KVgqPc4jyzhv7gH8Ky7FfMLbGcS9bJrKhIKOEaqnY5RnAkh8kh0lQP GobAKRpl3TNVbDchFbpwZe3emWMmpr+dtMw5xTucB/PixHZK55wXJ6C4Byn1dn4eF2wo LWdg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=kwKSbhTwe1sURT7PthXxteRn0w1xOxJogQ6ibhTwmw4=; b=OHXD6d+5LrhpQe4LCypsnM3jcJo/OGE556ORG7F9A4Hmr/zGprOsvIxIsWczf4uCiK ZpSnZ6Gx9XiigBbXX2KN6L6cfY30A9goMpK3bCoF5Lh586V6riL4h6eOzdm/oNsyfVHN fUQjznivGxl4usv40fFOQqpUYMEvQSi8Yf4TsSWd/5GZxpFd5G/nxbPcighWpkLloe8w VelRSD8+9tQI32J4/lim7jsMBKqagRL89tVmS3+C3nCdSpPYtjQdGUIwDxSNKJ0f7E7z r9zDE309y9CNXisDPlJLvmqC5kzxefpD33DCDN//HbwtJK7UAvibMiejSTmCub5BDSla rAgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :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=kwKSbhTwe1sURT7PthXxteRn0w1xOxJogQ6ibhTwmw4=; b=KM+CoGnJKfLAfViNfFCy9Ghs9QT3xYzj1TRQxLXkasyH8ejaOvpLCWfld7OnBXDOlE SHLtBENrT6uouRw+X9wZvCAmybm22yXNt4VVtpAxQ9hDllpdjoWFSGhwRgVRkQfHSBO9 KMdROW4/R5U0W9DMbzUMyqi09QfvE052g6Q8+QDdARNe21A0RSs9Jx6w0l70u4F6AzHb f1/6vSqt9Ve0yY/6CnuvdcerD8KrWLxNKJrZs/UEJDDrF/bNRJTdgiX+IZH2RLLV/0wc Obw7DrwGjl2jTL4gg+m0xhM4KfIaSGq5twgD5VKXmm9pZm1KZB5oMtEmwneNpoW1QYcl gbsw== X-Gm-Message-State: AHYfb5ibKZahh5qbl8g3IxOLzGfD/qsn4qdWH0icSbAS4xIukFEsTQOS 1rXjfm8hRBjkNSku X-Received: by 10.176.19.111 with SMTP id h44mr9957027uae.5.1502478560713; Fri, 11 Aug 2017 12:09:20 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.31.16 with SMTP id d16ls145143itd.4.gmail; Fri, 11 Aug 2017 12:09:19 -0700 (PDT) X-Received: by 10.31.153.84 with SMTP id b81mr94740vke.14.1502478559422; Fri, 11 Aug 2017 12:09:19 -0700 (PDT) In-Reply-To: <250415405.SNDfSfLC7e@tjmaciei-mobl1> X-Original-Sender: jmckesson@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:33840 Archived-At: ------=_Part_2226_1153724885.1502478558852 Content-Type: multipart/alternative; boundary="----=_Part_2227_1641056724.1502478558852" ------=_Part_2227_1641056724.1502478558852 Content-Type: text/plain; charset="UTF-8" On Friday, August 11, 2017 at 2:12:42 PM UTC-4, Thiago Macieira wrote: > > On sexta-feira, 11 de agosto de 2017 10:01:28 PDT Nicol Bolas wrote: > > `zstring_view` is conceptually a `string_view`. This means that it is a > > pointer+size, so `size()` is always O(1). But this also means that if > you > > try to put a literal in a `zstring_view`, it will have to invoke > > `char_traits::length` to get the length. This is good if you're actually > > going to use begin/end iterator pairs. But it's painful if you're just > > doing one-time forward iteration. > > > > `cstring_view` is just a `const char*` with a nice wrapper. It is just a > > pointer, which means `size()` is always O(n). But this also means that > > sticking a literal in it costs nothing. But if you try to use it with > > begin/end iterator pairs, you provoke an O(n) operation. > > int main(std::initializer_list) > > can be accomplished with a simple instruction inserted by the compiler at > the > beginning of main(), How, exactly? `cstring_view` would not be *required* to be implemented as identical to `const char*`, after all. So there's no way to could guarantee that the `argv` array would be equivalent to that. Also, it's not exactly a motivational use case for the type. -- 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/51add97a-3379-4b9e-9bd3-8972ed0e7636%40isocpp.org. ------=_Part_2227_1641056724.1502478558852 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Friday, August 11, 2017 at 2:12:42 PM UTC-4, Thiago Mac= ieira wrote:
On sexta-feira, 11= de agosto de 2017 10:01:28 PDT Nicol Bolas wrote:
> `zstring_view` is conceptually a `string_view`. This means that it= is a
> pointer+size, so `size()` is always O(1). But this also means that= if you
> try to put a literal in a `zstring_view`, it will have to invoke
> `char_traits::length` to get the length. This is good if you'r= e actually
> going to use begin/end iterator pairs. But it's painful if you= 're just
> doing one-time forward iteration.
>=20
> `cstring_view` is just a `const char*` with a nice wrapper. It is = just a
> pointer, which means `size()` is always O(n). But this also means = that
> sticking a literal in it costs nothing. But if you try to use it w= ith
> begin/end iterator pairs, you provoke an O(n) operation.

int main(std::initializer_list<std::cstring_view>)

can be accomplished with a simple instruction inserted by the compiler = at the=20
beginning of main(),

How, exactly? `cstring_view` = would not be required to be implemented as identical to `const char*= `, after all. So there's no way to could guarantee that the `argv` arra= y would be equivalent to that.

Also, it's not exactly a motivati= onal use case for the type.

--
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-proposa= ls+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/51add97a-3379-4b9e-9bd3-8972ed0e7636= %40isocpp.org.
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