220 30018 article Path: news.gmane.org!.POSTED!not-for-mail From: "dgutson ." Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: join/split for string & string_view Date: Sun, 25 Dec 2016 13:17:36 -0300 Lines: 292 Approved: news@gmane.org Message-ID: References: <172d08f0-a3da-4b9e-bfdd-985fb1f527c8@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=94eb2c05f4da1c1eec05447df558 X-Trace: blaine.gmane.org 1482682663 2515 195.159.176.226 (25 Dec 2016 16:17:43 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 25 Dec 2016 16:17:43 +0000 (UTC) Cc: lnaltidev@gmail.com To: std-proposals Original-X-From: std-proposals+bncBDE3NBMV6UFBBIPC77BAKGQE3WVXUZY@isocpp.org Sun Dec 25 17:17:37 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yb0-f199.google.com ([209.85.213.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cLBUM-000802-Be for gclcip-std-proposals@m.gmane.org; Sun, 25 Dec 2016 17:17:34 +0100 Original-Received: by mail-yb0-f199.google.com with SMTP id 10sf114570896ybz.4 for ; Sun, 25 Dec 2016 08:17:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc: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=7XT0af2kMPyZU1scrLUE4ng2y5BMT9BPp2ABPR6xtuI=; b=ObFeodCUTzA9wqACW+a5Hvle++gunJXb6SO0wCuPYshCmXJcctlr5Jl/Payvlm5n0M 6ayGoDOwQNoA/clsvdDWF6L4ziV59Z1LBJ8pEjUzWqnpGOu9l5yk46YyBv3KOIFRjbKP G4qqknxPuGBC0mYbzPyQQn9vD51vasMA+9CEOZ27LXNr8DmHsLE6WdDAj2/ZQpDP7zK+ PCZ9TKd9gch5klNY9Jwg+X11KvEI1m2BdX8Cxpt99FifNAxcXhXw767JfHB4Kg7UtNYE K0Z4Gr+zBJuyoLwV3aTJdo/hD2Pp1KD+SBHNBg5ZvOu5DSMlAwWqiAX/CKbpXvvzP1Du GiAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc: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=7XT0af2kMPyZU1scrLUE4ng2y5BMT9BPp2ABPR6xtuI=; b=nozbHknejDExNq0MnFg3TWY9OfKAriPswUsTB49Lze5/RgKlGxZ4j+X/rpS8sdEmsN ZyvRqLkp1pR7nbn4tmw8fDzlUiS8YIob/JLY7Mqx1HaxoC8iBNq+a72/JdEmdJhfC853 IiNleotzVWtsBaL6D6m9tjxasG0ACwt1wl9t/gdz5eCAEN4JJ/WwHjfn5lcMsViPRwAA BO19HN+SXfTT8duH/aqKBgkrRL4VeXHx7lNiYCYiTpnWdQZBBfl+WYS5TSLBFRx/PXrU Dakm5G05O3Ks5E2aK2tmtbcwyk5UENDIQeK0OqTNP1C6negVcQGq5LzllXr3bc3vyg2n /B0A== X-Gm-Message-State: AIkVDXL9+ljQIyGBOoGC19JBUAGmTtbyb0Doh3GEhcp/QLN0LWGQQgyAoBNtAPwH4SBjlw== X-Received: by 10.129.92.2 with SMTP id q2mr7037659ywb.57.1482682658760; Sun, 25 Dec 2016 08:17:38 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.147.7 with SMTP id v7ls7575271iod.6.gmail; Sun, 25 Dec 2016 08:17:37 -0800 (PST) X-Received: by 10.107.28.12 with SMTP id c12mr13532111ioc.223.1482682657631; Sun, 25 Dec 2016 08:17:37 -0800 (PST) Original-Received: from mail-it0-x236.google.com (mail-it0-x236.google.com. [2607:f8b0:4001:c0b::236]) by mx.google.com with ESMTPS id u186si6582957itf.113.2016.12.25.08.17.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Dec 2016 08:17:37 -0800 (PST) Received-SPF: pass (google.com: domain of danielgutson@gmail.com designates 2607:f8b0:4001:c0b::236 as permitted sender) client-ip=2607:f8b0:4001:c0b::236; Original-Received: by mail-it0-x236.google.com with SMTP id 75so39773786ite.1 for ; Sun, 25 Dec 2016 08:17:37 -0800 (PST) X-Received: by 10.36.216.70 with SMTP id b67mr20396937itg.5.1482682657407; Sun, 25 Dec 2016 08:17:37 -0800 (PST) Original-Received: by 10.36.79.210 with HTTP; Sun, 25 Dec 2016 08:17:36 -0800 (PST) Original-Received: by 10.36.79.210 with HTTP; Sun, 25 Dec 2016 08:17:36 -0800 (PST) In-Reply-To: <172d08f0-a3da-4b9e-bfdd-985fb1f527c8@isocpp.org> X-Original-Sender: danielgutson@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of danielgutson@gmail.com designates 2607:f8b0:4001:c0b::236 as permitted sender) smtp.mailfrom=danielgutson@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:30018 Archived-At: --94eb2c05f4da1c1eec05447df558 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable El 25/12/2016 12:41, "Nicol Bolas" escribi=C3=B3: On Sunday, December 25, 2016 at 5:32:44 AM UTC-5, lnal...@gmail.com wrote: > > Hello, > > > Most of modern language (D, Python, Java, C#, Go, Rust) got a split metho= d > on their string type, so I think it really make sense to have something > similar in C++. > All of those languages also only have a single string type. C++ has *hundreds*. Even the *standard library* has 2, and that doens't even count `const char*`. Having a `split` function that can *only* be used with the standard library string types is pathetic. Especially when it could be made to be used with any string type (that provides a conversion to `string_view`) with ease. If you want to suggest that `basic_string` and `string_view` should have member versions that call the non-member algorithms, fine. But the non-member function is where the actual work happens. > All of them returns a 'vector' and I think is the main waited result. > No. While we should not be ignorant of what other languages are doing, we also should not pretend that the design of other languages is a priori correct for C++. We should do what is best for C++. And one principle of C++ is that we do not make people pay for features they don't need to use. Forcing the return of a `vector` makes people pay for memory allocations that they may not use. I think it should not be required to mastering all subtilities of the STL > to do something a simple as that. > Master the subtleties of what? Of using a range? That should be an early lesson for C++ programmers; it's hardly deep metaprogramming magic. If you're going to be able to work in a language, you *need* to know its idioms. And ranges are very important idioms in C++. We shouldn't cater to the demographic of people who learn just the syntax of a language and then pretend that they know it. I think it should be possible to write : > auto MyResult=3D "my,csv,line"s.split(","); > myvar=3DMyResult[1]; > for(auto sv : MyResult) > > Here is what that code would look like under the guidelines I (and others) outlined previously: vector MyResult(split("my,csv,line", ",")); myvar =3D MyResult[1]; for(auto sv : MyResult) See how simple that is? This only allocates memory in `vector`'s constructor (so you're not needlessly allocating a `basic_string`, just for a string literal). Plus, if you just want the iteration, without the need for random access: for(auto sv : split("my,csv,line", ",")) This performs *zero* memory allocations. Why *shouldn't* this be the default? In C++, the default ought to be fast, where possible. I think there should also be a callback-oriented version by providing a callable template argument (e.g. lambda, std::function, function ptr, etc) which requires no memory allocation. Perhaps having multiple (like for stoi,l,ll) could be an option > No. A single function returning a range, as outlined above, can cover all of these cases effectively. --=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 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/172d08f0-a3da-4b9e- bfdd-985fb1f527c8%40isocpp.org .. --=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/CAFdMc-07FWpV07b3WSz0U%3DuDNHXM19xgBTH%3DCpt%3DK= vty4886FQ%40mail.gmail.com. --94eb2c05f4da1c1eec05447df558 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


El 25/12/2016 12:41, "Nicol Bolas" <jmckesson@gmail.com> escribi=C3=B3:
On Sunday, December 25, 2016 at 5:32:44 AM UTC-5, lnal...@gmail.com wrote:

Hello,


Most= of modern language (D, Python, Java, C#, Go, Rust) got a split=20 method on their string type, so I think it really make sense to have someth= ing=20 similar in C++.


All of those langu= ages also only have a single string type. C++ has hundreds. Even the= standard library has 2, and that doens't even count `const char= *`.

Having a `split` function that can only be used with the = standard library string types is pathetic. Especially when it could be made= to be used with any string type (that provides a conversion to `string_vie= w`) with ease.

If you want to suggest that `basic_string` and `strin= g_view` should have member versions that call the non-member algorithms, fi= ne. But the non-member function is where the actual work happens.
=C2=A0=

All of them returns a 'vector' and I think is the= main waited=20 result.


No.

While we should not= be ignorant of what other languages are doing, we also should not pretend = that the design of other languages is a priori correct for C++. We should d= o what is best for C++.

And one principle of C++ is that we do not m= ake people pay for features they don't need to use. Forcing the return = of a `vector` makes people pay for memory allocations that they may not use= ..

I think it should=20 not be required to mastering all subtilities of the STL to do something a s= imple=20 as that.


Master the subtleties of what= ? Of using a range? That should be an early lesson for C++ programmers; it&= #39;s hardly deep metaprogramming magic.

If you're going to be a= ble to work in a language, you need to know its idioms. And ranges a= re very important idioms in C++. We shouldn't cater to the demographic = of people who learn just the syntax of a language and then pretend that the= y know it.

I think it should be possible to write :

auto MyResult=3D<= span style=3D"color:#000"> "my,csv,l= ine"s.split(",");
myvar=3DMyResult[1];
for(auto sv : MyResult)

=
Here is what that code would look like under the guidelines I (and othe= rs) outlined previously:

vector <= /span>MyResult(split("my,csv,lin= e", ","));
m= yvar =3D MyResult[1];=
for(auto sv : MyResult)

See how sim= ple that is? This only allocates memory in `vector`'s constructor (so y= ou're not needlessly allocating a `basic_string`, just for a string lit= eral).

Plus, if you just want the iteration, without the need for ra= ndom access:

for(= auto sv : split("my,csv= ,line", ","))

This performs zero memory allocations. Why sho= uldn't this be the default? In C++, the default ought to be fast, w= here possible.

I think there should also be a callback-ori= ented version by providing a callable template argument (e.g. lambda, std::= function, function ptr, etc) which requires no memory allocation.


<= div dir=3D"ltr">

Perhaps having multiple (like for stoi,l,ll) could be an option


No. A single function returning a range= , as outlined above, can cover all of these cases effectively.

--
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.
To view this discussion on the web visit = https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/172d= 08f0-a3da-4b9e-bfdd-985fb1f527c8%40isocpp.org.

--
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.
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To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAFdMc-07FW= pV07b3WSz0U%3DuDNHXM19xgBTH%3DCpt%3DKvty4886FQ%40mail.gmail.com.
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