220 34223 <2f48bdde-a6b6-473f-96ec-8836fd8de463@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Idea: Extension of structured bindings to definition of structs Date: Wed, 30 Aug 2017 08:02:27 -0700 (PDT) Lines: 113 Approved: news@gmane.org Message-ID: <2f48bdde-a6b6-473f-96ec-8836fd8de463@isocpp.org> References: <59dcbbbc-c536-4b7b-9c88-0638fb0cd58a@technion.ac.il> <7b9bf263-d3ca-42bf-aed6-4c7606782a28@isocpp.org> <1762295.OciJaA9sdk@tjmaciei-mobl1> <74349bfe-bb5a-a2ce-4142-5d46103d1d9f@technion.ac.il> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_9631_16249119.1504105347654" X-Trace: blaine.gmane.org 1504105389 21961 195.159.176.226 (30 Aug 2017 15:03:09 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 30 Aug 2017 15:03:09 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBBFHTPGQKGQEWDDCQXQ@isocpp.org Wed Aug 30 17:03:05 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f198.google.com ([209.85.161.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dn4Vf-0003ra-51 for gclcip-std-proposals@m.gmane.org; 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Wed, 30 Aug 2017 08:02:29 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.183.212 with SMTP id h203ls4360128iof.24.gmail; Wed, 30 Aug 2017 08:02:28 -0700 (PDT) X-Received: by 10.31.155.132 with SMTP id d126mr20060vke.17.1504105348170; Wed, 30 Aug 2017 08:02:28 -0700 (PDT) In-Reply-To: <74349bfe-bb5a-a2ce-4142-5d46103d1d9f@technion.ac.il> 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:34223 Archived-At: ------=_Part_9631_16249119.1504105347654 Content-Type: multipart/alternative; boundary="----=_Part_9632_1848123028.1504105347654" ------=_Part_9632_1848123028.1504105347654 Content-Type: text/plain; charset="UTF-8" On Wednesday, August 30, 2017 at 3:59:43 AM UTC-4, Eyal Rozenberg wrote: > > You would be using an unnamed struct for the same reason you use an > "unnamed type" for non-struct variables with auto. We write: > > auto x = expr; > > although we could write > > using whatever_t = decltype(expr); > > // ... > > whatever_t x = expr; > > except we do it for several values which are grouped together in a > struct. But the reason I'm using `auto` is because I either: 1) Don't need to write the name of the type, since it is obvious by inspection 2) Do not want to write the name of the type, since it's long, complex, etc Why do I need to create a *type* that contains a bunch of such variables? And why would I need to do it *inline* like this? If I'm creating a collection of values, then that collection generally has some meaning to the program. There are probably several functions that take it as parameters, or there are member functions that operate on it, or whatever. So what is the point of having this unnamed struct that uses automatically-deduced values? Who am I going to pass it to? What operations am I going to perform on it? Why did I make a struct out of it instead of just having a number of loose variables? The second option does the exact same thing, but it's annoying > and verbose. > -- 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/2f48bdde-a6b6-473f-96ec-8836fd8de463%40isocpp.org. ------=_Part_9632_1848123028.1504105347654 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Wednesday, August 30, 2017 at 3:59:43 AM UTC-4, Eyal Ro= zenberg wrote:
You would be usi= ng an unnamed struct for the same reason you use an
"unnamed type" for non-struct variables with auto. We write:

=C2=A0 auto x =3D expr;

although we could write

=C2=A0 using whatever_t =3D decltype(expr);

=C2=A0 // ...

=C2=A0 whatever_t x =3D expr;

except we do it for several values which are grouped together in a
struct.

But the reason I'm using `auto` is bec= ause I either:

1) Don't need to write the name of the type, sinc= e it is obvious by inspection
2) Do not want to write the name of the ty= pe, since it's long, complex, etc

Why do I need to create a t= ype that contains a bunch of such variables? And why would I need to do= it inline like this?

If I'm creating a collection of val= ues, then that collection generally has some meaning to the program. There = are probably several functions that take it as parameters, or there are mem= ber functions that operate on it, or whatever.

So what is the point = of having this unnamed struct that uses automatically-deduced values? Who a= m I going to pass it to? What operations am I going to perform on it? Why d= id I make a struct out of it instead of just having a number of loose varia= bles?

The second = option does the exact same thing, but it's annoying
and verbose.

--
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/2f48bdde-a6b6-473f-96ec-8836fd8de463= %40isocpp.org.
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