220 20382 <2967AF29-EF2A-4BE8-8A91-737BD7EB2C1A@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Usability improvement: Unambiguously resolve overloaded functions when passed as function parameters Date: Thu, 10 Sep 2015 18:29:26 +0800 Lines: 103 Approved: news@gmane.org Message-ID: <2967AF29-EF2A-4BE8-8A91-737BD7EB2C1A@gmail.com> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_1F082AA6-39C1-4266-A7AD-1AECE78C8035" X-Trace: ger.gmane.org 1441880998 24702 80.91.229.3 (10 Sep 2015 10:29:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 10 Sep 2015 10:29:58 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBDFXYWXQKGQE2UOYP3Q@isocpp.org Thu Sep 10 12:29:46 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f200.google.com ([209.85.213.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZZz6k-0007Hs-EB for gclcip-std-proposals@m.gmane.org; Thu, 10 Sep 2015 12:29:34 +0200 Original-Received: by igbbp9 with SMTP id bp9sf32482943igb.3 for ; Thu, 10 Sep 2015 03:29:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:content-type:message-id:mime-version :subject:date:references:to:in-reply-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=q8tvnsrGU+P+oJV+Yp5OYkjoUxkzlSOpqk1Cv+RsIEU=; b=TaO0E7vfnAQrvtvqnx6F8KQ3J/6qoRvp/nwwJcumy/ByWzYvZE3GvkxYhDtrZAbbEj C0Ynirhr3escZ8SlAAJyDuscgigbSdtIimq1b6oBW1OWl+CfnrtmnUP+RAzN9n+4IbYK IIS6yKn12y7G15RooQJxL2PXHkdhtYGVwOuxxctu6l2o4xaXhBGg3rCwy8kAwDHULmDv ZXgmMeh1j+IWDtUg0OP0XOF1HKq/sLY4VifN6C3+ucqFjRodtPAEgqtp338rTEokXfrO 8BReVbs9PQmOGPi2GgUyBrBCZsTGHPpwqvQ599bz1whWNaMTr2y5Lfd3L/MMHFr/RJPN U8fA== X-Gm-Message-State: ALoCoQk2q9/bctqx5dgVokMaVR0XGPH3crI9vA8AZI12M9DNQwp7j/7ThfcOPigh1LmWvzZoHx8n X-Received: by 10.50.110.40 with SMTP id hx8mr2077986igb.2.1441880973468; Thu, 10 Sep 2015 03:29:33 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.178.148 with SMTP id cy20ls181311igc.32.gmail; Thu, 10 Sep 2015 03:29:32 -0700 (PDT) X-Received: by 10.69.12.162 with SMTP id er2mr82737048pbd.24.1441880972786; Thu, 10 Sep 2015 03:29:32 -0700 (PDT) Original-Received: from mail-pa0-x231.google.com (mail-pa0-x231.google.com. [2607:f8b0:400e:c03::231]) by mx.google.com with ESMTPS id vy5si18576708pac.2.2015.09.10.03.29.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Sep 2015 03:29:32 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::231 as permitted sender) client-ip=2607:f8b0:400e:c03::231; Original-Received: by padhy16 with SMTP id hy16so39675677pad.1 for ; Thu, 10 Sep 2015 03:29:32 -0700 (PDT) X-Received: by 10.66.121.74 with SMTP id li10mr71764545pab.73.1441880972344; Thu, 10 Sep 2015 03:29:32 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.54.184]) by smtp.gmail.com with ESMTPSA id rz9sm2764267pbb.61.2015.09.10.03.29.30 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 10 Sep 2015 03:29:31 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.2104) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::231 as permitted sender) smtp.mailfrom=potswa@gmail.com; dkim=pass header.i=@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-Spam-Checked-In-Group: std-proposals@isocpp.org 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:20382 Archived-At: --Apple-Mail=_1F082AA6-39C1-4266-A7AD-1AECE78C8035 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9309=E2=80=9310, at 12:16 PM, Germ=C3=A1n Diago wrote: >=20 > Is there any interest in solving this problem? Certainly. See N3617 which opened EWG 65 . The problem appears like it could be amenable to expression aliases. Howeve= r, it=E2=80=99s tricky to fit expression aliases into either the type syste= m or into parameter passing. Perhaps you could have an alias parameter decl= ared with auto to imply function templating. decltype(auto) bind5( auto [&]f ) { return f( 5 ); // Evaluate the argument expression here. } Deducing class template parameters from an initializer (i.e. parameter) cou= ld also help to decide exactly what the wrapper is, allowing e.g. implicit = conversion of the overloaded name to std::function when the receiver isn=E2= =80=99t a template. Sorry to be vague, but my personal suspicion is that the best solution lies= in the intersection of these several speculative solution spaces. --=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/. --Apple-Mail=_1F082AA6-39C1-4266-A7AD-1AECE78C8035 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9309= =E2=80=9310, at 12:16 PM, Germ=C3=A1n Diago <germandiago@gmail.com> wrote:

Is there any interest in = solving this problem?

Certainly. See N3= 617 which opened EWG 65.

The problem appears like it could be amenable to= expression aliases. However, it=E2=80=99s tricky to fit expression aliases= into either the type system or into parameter passing. Perhaps you could h= ave an alias parameter declared with auto= to imply function templating.

<= /div>
decltype(auto) bind5= ( auto [&]f ) {
    return f( 5 ); // Evaluate the argument expression her= e.
}

Deducing class tem= plate parameters from an initializer (i.e. parameter) could also help to de= cide exactly what the wrapper is, allowing e.g. implicit conversion of the = overloaded name to std::function&n= bsp;when the receiver isn=E2=80=99t a template.

Sorry to be vague, but my personal suspicion= is that the best solution lies in the intersection of these several specul= ative solution spaces.

--

---
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