220 20413 article Path: news.gmane.org!not-for-mail From: Arthur O'Dwyer Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Usability improvement: Unambiguously resolve overloaded functions when passed as function parameters Date: Fri, 11 Sep 2015 01:16:27 -0700 (PDT) Lines: 106 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_749_64981022.1441959387347" X-Trace: ger.gmane.org 1441959391 17799 80.91.229.3 (11 Sep 2015 08:16:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 11 Sep 2015 08:16:31 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDLZJYWNDQINZG6KV4CRUBDH3JA7O@isocpp.org Fri Sep 11 10:16:31 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f198.google.com ([209.85.220.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZaJVV-0003C7-GL for gclcip-std-proposals@m.gmane.org; Fri, 11 Sep 2015 10:16:29 +0200 Original-Received: by qkdj7 with SMTP id j7sf9422003qkd.1 for ; Fri, 11 Sep 2015 01:16:28 -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 :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=nHFP1dZn0uT0MD/f/xBf6RS2QP3Ruu8qIcAVg1yAdoA=; b=J5FiqEeVFM71uWlfc3KhYDWYYoLjtay/+fXsLeT7HzzxnenA3OcoWDngm545Bb8kpj HoPgwyJ2A76ltiy/ZwASueN4/tVO4fHBH2KxrfIQG7C70JkmKMTY/SX7EC3vnOI69ypM Ti0UKZ75qBIEhx4VDrSB31KH8fVaPfGvV+rlSx65iq3P44eP5qlnzN6Q1m6NleIriUoZ uHKWV9dKmUptLFCqePJC2Kkf59mVZ4kLI/gew+lXOxYWOWMXtZW6mGzIg8Dms1oFX48f qyrIGzO8/+suB/Fsh54im42zN/ROb68IMRowMwg5BQlSkCbFq/mHUOR213Bel/nWPWfY /53A== 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:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=nHFP1dZn0uT0MD/f/xBf6RS2QP3Ruu8qIcAVg1yAdoA=; b=bNlnw2+nGkH/XAlIQASKUHuqJMs+6h2ay/NDhhJjSKZlUZ3fDKCdOOSQVvNaHojKsz tGm3BcBPGqMdcsI7tlFI+oSsX+5MFMEnzJ05by3I70h+Fmz+DpLWZEaD4767SjW4WrzG nhiGQt3bRrkmiwszBEiTJ2vZFMJe9axwxxWR+RmDvNR+IVg80Jp8J2R8hwd11O7TecSA 7UVAfyOh+WlBGVraCZC62ubpkZABNHNE3NUhoxWtKz9CMWKljSfQZq0m8KkRkOq4kRFJ Tqss6DcDsHPPynS2Kh1g5B8FdnvK3SBJoVrH89s9XTN70djewNVeikW/Srs1e4CG4BRp RfuQ== X-Gm-Message-State: ALoCoQnjsg1Wrd2CJZUu36p2DGWkJ2nStWeAOXbcJlRYJKf+mhrBH132bygaEE9Xct/TFXtTWMwF X-Received: by 10.13.200.198 with SMTP id k189mr40455750ywd.46.1441959388683; Fri, 11 Sep 2015 01:16:28 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.66.229 with SMTP id i5ls455768igt.8.gmail; Fri, 11 Sep 2015 01:16:28 -0700 (PDT) X-Received: by 10.50.122.103 with SMTP id lr7mr9342igb.10.1441959388042; Fri, 11 Sep 2015 01:16:28 -0700 (PDT) In-Reply-To: X-Original-Sender: arthur.j.odwyer@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:20413 Archived-At: ------=_Part_749_64981022.1441959387347 Content-Type: multipart/alternative; boundary="----=_Part_750_1016620126.1441959387348" ------=_Part_750_1016620126.1441959387348 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wednesday, September 9, 2015 at 9:16:28 PM UTC-7, Germ=C3=A1n Diago wrot= e: > > Hello everyone, > > A usability problem I found and it is quite annoying and could show in=20 > many scenarios, > and potentially in generic scenarios, is the following one: > > > void f(); > void f(int, float); > void f(int); > > > auto bound_f =3D bind(f, std::placeholders::_1, 3.8f); //Ambigous cal= l > =20 > Instead we must do this, which is annoying, but also advanced for=20 > non-expert users (usability problem): > > auto bound_f =3D bind (static_cast(f),=20 > std::placeholders::_1, 3.8f); > An alternative in C++14 is auto bound_f =3D [](auto x, ...){ return f(x, 3.8f); }; and then if you don't actually need the "..." part, you could drop it,=20 which would make your code read more cleanly. auto bound_f =3D [](auto x){ return f(x, 3.8f); }; I have thought it would be nice to have some sort of macro like #define OVERLOAD_SET(f) [](auto&&... args) { return=20 f(std::forward(args)...); } but I've never actually found myself *needing* it in practice, yet. --=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_750_1016620126.1441959387348 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Wednesday, September 9, 2015 at 9:16:28 PM UTC-7, Germ= =C3=A1n Diago wrote:
Hello everyone,

A usability problem I found and it is quite= annoying and could show in many scenarios,
and potentially in generic s= cenarios, is the following one:


=C2=A0=C2=A0=C2=A0 void f();
= =C2=A0=C2=A0=C2=A0 void f(int, float);
=C2=A0=C2=A0=C2=A0 void f(int);

=C2=A0=C2=A0=C2=A0 auto bound_f =3D bind(f, std::placeholders::_1= , 3.8f); //Ambigous call
=C2=A0
Instead we must do this, which is ann= oying, but also advanced for non-expert users (usability problem):

= =C2=A0=C2=A0=C2=A0 auto bound_f =3D bind (static_cast<void (*)(int, floa= t)>(f), std::placeholders::_1, 3.8f);

An alternative in C++14 is

=C2=A0 =C2=A0 a= uto bound_f =3D [](auto x, ...){ return f(x, 3.8f); };

=
and then if you don't actually need the "..." part, you = could drop it, which would make your code read more cleanly.

=
=C2=A0 =C2=A0 auto bound_f =3D [](auto x){ return f(x, 3.8f= ); };

I have thought it would be nice to hav= e some sort of macro like

=C2=A0 =C2=A0 #define OV= ERLOAD_SET(f) [](auto&&... args) { return f(std::forward<decltyp= e(args)>(args)...); }

but I've never actual= ly found myself *needing* it in practice, yet.

--

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