220 11465 <5bae7c28-542c-4d00-ad85-6025bb98e9b8@isocpp.org> article Path: news.gmane.org!not-for-mail From: Matthew Fioravante Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Named function parameters using anonymous structs for C and C++ Date: Mon, 16 Jun 2014 22:18:18 -0700 (PDT) Lines: 191 Approved: news@gmane.org Message-ID: <5bae7c28-542c-4d00-ad85-6025bb98e9b8@isocpp.org> References: <72c49240-547b-4bf6-8b27-aff6a61c1272@isocpp.org> <29C6D83B-BD31-42A9-B7BD-2C797E3FE58C@gmail.com> <26565335.62izyTXvIe@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_1914_15351143.1402982298273" X-Trace: ger.gmane.org 1402982305 31748 80.91.229.3 (17 Jun 2014 05:18:25 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 17 Jun 2014 05:18:25 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDELF54RTIGRBGU776OAKGQEKBNMV3I@isocpp.org Tue Jun 17 07:18:20 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f199.google.com ([209.85.213.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Wwlmm-0000nm-Bi for gclcip-std-proposals@m.gmane.org; Tue, 17 Jun 2014 07:18:20 +0200 Original-Received: by mail-ig0-f199.google.com with SMTP id h18sf14430750igc.10 for ; Mon, 16 Jun 2014 22:18:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; 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 :content-type; bh=tgOsZhRHmetQwPgzmkVMp3d6KMrTQ2Fmu17WhX5duXk=; b=rOa9thlQ5gjGx7RQr4sPVgAZ9tf7myVIVJ4kJSX5ZRTGUKIWlmKqUoHJa8LJE/OH5r uY+Z/H+7QHpjyXPUmNSdrMfraIwaF8LU4d95KQr1vFVFDYmBcuMiOxhL4q77HItPhL52 rrL8o52vYtZpPifRJQ2LiEoMEHdq3Jhic2Upefjj+cONPUfN7CmFXfT2hPZChFkpLofl XuG0I3fU3SJFe3Vfz41vGipdQzj5NXbG2yry9tyonGcDMMad5c6PfnQwTp96bQBQ4muJ hf2osGHK9Htvb7Ev0C5NXzDEytJwSib1qozEWqm9IDvhSWPn1P0++WlRUP03WkQ1JE3o EAyQ== 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: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:content-type; bh=tgOsZhRHmetQwPgzmkVMp3d6KMrTQ2Fmu17WhX5duXk=; b=MDaIWlIDjo6WU3cj596ABWVqHFNwE47OM8FpjTa+TlLIfzp7p9X9ojnzzZ7Y0LuI0u heiXcbwLzy1slGQeecO09XHFivDJ+s3zQjUgi6xCPOvQlfCKgoD/WwvCm6ouTgigXlE9 HhBH1Tac9XuE6M9K2gplVuZUeB9XeLCSjvOLbrhoHGSxdbX9f9oo9A7zJwUT7H2WuUyb NO8aDQyvCx4dB3tAU+dtwh7SvSObKVtnO2108ZlEFWhgXRUw9UJ2WSYumKRHyhNqbdyE oC8L46p+PtxKPXGTR+krD4mGrmeXzp/qRuI3jqExStqiwaqaMLavr1T+HUi5GKBSz+hq +AZw== X-Gm-Message-State: ALoCoQkfez7HgXH6wYRI1tbaGXDHOQkX/7PAtDwTlSlBlIJ1Eq2xNQlcDGiguQPShca1xFFCc3cq X-Received: by 10.42.233.133 with SMTP id jy5mr1267059icb.32.1402982299432; Mon, 16 Jun 2014 22:18:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.27.138 with SMTP id 10ls4734840qgx.9.gmail; Mon, 16 Jun 2014 22:18:18 -0700 (PDT) X-Received: by 10.140.107.35 with SMTP id g32mr426387qgf.2.1402982298862; Mon, 16 Jun 2014 22:18:18 -0700 (PDT) In-Reply-To: <26565335.62izyTXvIe@tjmaciei-mobl4> X-Original-Sender: fmatthew5876@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:11465 Archived-At: ------=_Part_1914_15351143.1402982298273 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tuesday, June 17, 2014 1:10:40 AM UTC-4, Thiago Macieira wrote: > > Em ter 17 jun 2014, =C3=A0s 12:43:19, David Krauss escreveu:=20 > > On 2014-06-17, at 10:46 AM, Matthew Fioravante >=20 > wrote:=20 > > > The original style:=20 > > >=20 > > > int foo(int a, int b, string c);=20 > > > foo(.a =3D 0, .b =3D 1, .c =3D "Hello");=20 > > >=20 > > > Pros:=20 > > > - Very simple=20 > > > - No ABI changes=20 > > > - All legacy code immediately becomes named function enabled=20 > >=20 > > > Cons:=20 > > The big con is that without ABI support, there's no overloading. My=20 > example=20 > > wouldn't work because both rect::rect overloads would mangle to the sam= e=20 > > name.=20 > > Use a tag struct as a differentiator:=20 > > struct TopLeftBottomRight {};=20 > rect(int top, int left, int bottom, int right, TopLeftBottomRight= =20 > =3D {})=20 > =20 > struct TopLeftWidthHeight {};=20 > rect(int top, int left, int width, int height, TopLeftWidthHeight= =20 > =3D {});=20 > > That's one way to do it, if we cannot come up with a nice naming rule. > > - Cannot use named syntax when calling via a function pointer, since=20 > the=20 > > > type has no concept of parameter names. - Requires some language=20 > changes=20 > > > to enable the callsite syntax=20 > > > - Argument names while not part of the ABI, are now part of the API.= =20 > You=20 > > > cannot change the names or you will break callers.=20 > > This is sort-of inherent to the feature, but it suggests that having=20 > foreign=20 > > (member declaration) syntax for named parameters is actually a good=20 > thing.=20 > > You can specify parameter names in the function pointer syntax...=20 > But they are meaningless, and I don't want to try to propose we change the= =20 type system for function pointers. You might be able to extract the names= =20 in simple cases, but when it comes to templates, auto, and decltype it=20 could get very messy. =20 > > --=20 > Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org=20 > Software Architect - Intel Open Source Technology Center=20 > PGP/GPG: 0x6EF45358; fingerprint:=20 > E067 918B B660 DBD1 105C 966C 33F5 F005 6EF4 5358=20 > > --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. ------=_Part_1914_15351143.1402982298273 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Tuesday, June 17, 2014 1:10:40 AM UTC-4, Thiago= Macieira wrote:
Em ter 17 jun = 2014, =C3=A0s 12:43:19, David Krauss escreveu:
> On 2014-06-17, at 10:46 AM, Matthew Fioravante <fmatth...@gmail.com>=20
wrote:
> > The original style:
> >=20
> > int foo(int a, int b, string c);
> > foo(.a =3D 0, .b =3D 1, .c =3D "Hello");
> >=20
> > Pros:
> > - Very simple
> > - No ABI changes
> > - All legacy code immediately becomes named function enabled
>=20
> > Cons:
> The big con is that without ABI support, there's no overloading. M= y example
> wouldn't work because both rect::rect overloads would mangle to th= e same
> name.

Use a tag struct as a differentiator:

        struct TopLeftBottomRig= ht {};
        rect(int top, int left,= int bottom, int right, TopLeftBottomRight =3D {})
        
        struct TopLeftWidthHeig= ht {};
        rect(int top, int left,= int width, int height, TopLeftWidthHeight =3D {});

That's one way to do it, if we cannot come up with a = nice naming rule.

> > - Cannot use named syntax when calling via a function poi= nter, since the
> > type has no concept of parameter names. - Requires some langu= age changes
> > to enable the callsite syntax
> > - Argument names while not part of the ABI, are now part of t= he API. You
> > cannot change the names or you will break callers.
> This is sort-of inherent to the feature, but it suggests that havi= ng foreign
> (member declaration) syntax for named parameters is actually a goo= d thing.

You can specify parameter names in the function pointer syntax...

But they are meaningless, and I don't = want to try to propose we change the type system for function pointers. You= might be able to extract the names in simple cases, but when it comes to t= emplates, auto, and decltype it could get very messy.

<= div> 

--=20
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4= 5358

--

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