220 30020 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 13:20:48 -0300 Lines: 371 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=94eb2c0b1dde88c4c605447e007e X-Trace: blaine.gmane.org 1482682860 26385 195.159.176.226 (25 Dec 2016 16:21:00 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 25 Dec 2016 16:21:00 +0000 (UTC) To: std-proposals Original-X-From: std-proposals+bncBDE3NBMV6UFBBYPD77BAKGQEXMCAUDA@isocpp.org Sun Dec 25 17:20:55 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f198.google.com ([209.85.217.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cLBXR-0005Dt-Jo for gclcip-std-proposals@m.gmane.org; Sun, 25 Dec 2016 17:20:45 +0100 Original-Received: by mail-ua0-f198.google.com with SMTP id i68sf128489562uad.3 for ; Sun, 25 Dec 2016 08:20:50 -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 :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=7rHhc7n2gUfTDTm7V56mjcXuQE18mYCcglwiNgE/sQE=; b=v46JZHKvxthrMm7NybScQVHpMVGUbb8yq5ek4sKClC8dvHaSMEvmn7u4Z2WvofwlEg JtK+CcnX6IVhqw1BCqDiDoF2vi4hCedTl0+D/7Dzq1i1Eyf1gz6NMZWQt7zOw/p4DeQl Zp+vUtse1vNmwEM45TUG/E16XVOTRbMjVL3wQbDsbzIx4NjsFHRiSQi/LyraWqVqABJl BYbFLxaos0p3mqtVx++8RTuV3I+1xmZBm4kr/NQkr/jd7lK+YdYTFtIFY8z1qA1h689x ZOz/MciMKvKuguYksR/dOf9pt4hYw8D19JCwb2/f7dqPDRi5rDzC+F7fS1T338LtIzNW GiSQ== 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: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=7rHhc7n2gUfTDTm7V56mjcXuQE18mYCcglwiNgE/sQE=; b=L8UsY4gmxlH4dTgtAP12yPkiZMWvL7NRiTOXRaIh4DeM22pZvPeWcXYgF7KSMZYisU hQ25LeNkzfBT19bCD/WojZxrwShtefkAPP7hqDHWjwq7S5MwtM/pCdjyyZgLOhNPjm8I l5bXFwpg5qs0ns3unjRAkrZSdo16TAbKgurpfZQg4h1bb1/rxDykbaDPH8V+dt2P8gMu vRmteccv6A3QwxYAJTNExIxkCCKVMbgGhDQ77DvVS98RPxGN7zfH2AuI5EGfHC3FD2Vi dFZkmC8iWHgH8/0S5NOaKfg5cw3/AZctkg8wK2bX5Zvv4xeEFO/LPTMflIVGLCulv2Sa PJVQ== X-Gm-Message-State: AIkVDXKyzlg1DPtNgLlXOlCaCezn23S5fhSrmBey0Ly0J+Y09w2W3OnFaw2z4Vfy6Nl9qw== X-Received: by 10.159.53.7 with SMTP id o7mr11021019uao.26.1482682850284; Sun, 25 Dec 2016 08:20:50 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.124.208 with SMTP id a199ls6312937itd.5.gmail; Sun, 25 Dec 2016 08:20:49 -0800 (PST) X-Received: by 10.36.55.137 with SMTP id r131mr23262932itr.86.1482682849412; Sun, 25 Dec 2016 08:20:49 -0800 (PST) Original-Received: from mail-it0-x22f.google.com (mail-it0-x22f.google.com. [2607:f8b0:4001:c0b::22f]) by mx.google.com with ESMTPS id n67si8222535ith.5.2016.12.25.08.20.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Dec 2016 08:20:49 -0800 (PST) Received-SPF: pass (google.com: domain of danielgutson@gmail.com designates 2607:f8b0:4001:c0b::22f as permitted sender) client-ip=2607:f8b0:4001:c0b::22f; Original-Received: by mail-it0-x22f.google.com with SMTP id o141so116352764itc.0 for ; Sun, 25 Dec 2016 08:20:49 -0800 (PST) X-Received: by 10.36.252.65 with SMTP id b62mr21343426ith.38.1482682849076; Sun, 25 Dec 2016 08:20:49 -0800 (PST) Original-Received: by 10.36.79.210 with HTTP; Sun, 25 Dec 2016 08:20:48 -0800 (PST) Original-Received: by 10.36.79.210 with HTTP; Sun, 25 Dec 2016 08:20:48 -0800 (PST) In-Reply-To: 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::22f 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:30020 Archived-At: --94eb2c0b1dde88c4c605447e007e Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable s/allocators/iterators/ El 25/12/2016 13:20, "dgutson ." escribi=C3=B3: > > > El 25/12/2016 13:17, "dgutson ." escribi=C3=B3: > > > > 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 >> method 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 als= o > 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 t= o > the demographic of people who learn just the syntax of a language and the= n > 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 f= or > 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. > > > > BTW, this should work with any container that provides allocators, > containing any type equal-comparable: > > vector v; > split(v, 1, [](int x){}); > > > > > 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 > "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/is > ocpp.org/d/msgid/std-proposals/172d08f0-a3da-4b9e-bfdd-985fb > 1f527c8%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-2Fgm3A2JjbERdCeFqDDFFTHhWFLPEr6Jw4uPp2dw1= Pbg%40mail.gmail.com. --94eb2c0b1dde88c4c605447e007e Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
s/allocators/iterators/
<= br>
El 25/12/2016 13:20, "dgutson ." &l= t;danielgutson@gmail.com> = escribi=C3=B3:


El 25/12/2016 13:17, "dgutson ." <danielgutson@gmail.com> escribi= =C3=B3:
<= br>

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,


Mos= t 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 ret= urns 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 thin= k 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 MyRes= ult(split("my,= csv,line", ","));
myvar =3D MyResult[1];
<= /span>for(auto sv : MyRes= ult)
=

See how simple that is? This only allocates memory in `vector`= 9;s constructor (so you're not needlessly allocating a `basic_string`, = just for a string literal).

Plus, if you just want the iteration, wi= thout the need for random access:

for(<= /span>auto sv : split("my,csv,line", = ","))

Thi= s 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, functi= on ptr, etc) which requires no memory allocation.
<= /div>


BTW, this should work with any container that provides allo= cators, containing any type equal-comparable:

vector<int> v;
split(v, = 1, [](int x){});



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.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit htt= ps://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAFdMc-2Fgm3A2Jjb= ERdCeFqDDFFTHhWFLPEr6Jw4uPp2dw1Pbg%40mail.gmail.com.
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