220 16328 article Path: news.gmane.org!not-for-mail From: ilja.j.honkonen@nasa.gov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Succinct declaration of metavariables Date: Tue, 17 Feb 2015 07:07:58 -0800 (PST) Lines: 331 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_3727_95280582.1424185678998" X-Trace: ger.gmane.org 1424185688 8160 80.91.229.3 (17 Feb 2015 15:08:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 17 Feb 2015 15:08:08 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC65R5PESMDBBT5SRWTQKGQEU37DL6Q@isocpp.org Tue Feb 17 16:08:08 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f197.google.com ([209.85.213.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YNjks-0002Y7-0c for gclcip-std-proposals@m.gmane.org; Tue, 17 Feb 2015 16:08:06 +0100 Original-Received: by mail-ig0-f197.google.com with SMTP id a13sf241845660igq.0 for ; Tue, 17 Feb 2015 07:08:00 -0800 (PST) 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:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=kHHxByapzKbhIWvqGtBjD6z6lufgOi1JQR3mXxSnzQs=; b=cOOQCSm5ctFFMTds/3cwsZtA1nSDL1nLx6CStudQjbwHL3T6HhVaaNXNDmvbk2kFOe H7umkdmXfG+1VSYPjflnMLUuohdqkpdtMBj729cnIrvsaphPBFNq6iBS+Nn2mNqYVzt3 DHeyHm9zjTKONNPJtbKpMJWKigqPRUJHEhMW2u/Ys4B5M0xvkpFK7A+0CfMShTxRGU7D m2YJTN+XPiiEJs9oDEm7bwC0TBSW6jUit/mfhg1XfGvuhtz5hj2uSP+oG9/i0aky/UTr CqjQKv3+kbKBXaJSvc2xwDV4LNC9VojYjlpBkP1emer7RiVeOJsxG/bKZmG/9WC0KAay 003w== X-Gm-Message-State: ALoCoQkJ6kZZ55S6BfUd+r/71gPgLUSyUhvrWjIN9VLy3w9r99E9z1h0WFB5J99o1qfoGWXjz9Sj X-Received: by 10.182.78.69 with SMTP id z5mr25493612obw.4.1424185680060; Tue, 17 Feb 2015 07:08:00 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.38.167 with SMTP id t36ls2986493qgt.68.gmail; Tue, 17 Feb 2015 07:07:59 -0800 (PST) X-Received: by 10.140.21.113 with SMTP id 104mr96452qgk.11.1424185679307; Tue, 17 Feb 2015 07:07:59 -0800 (PST) X-Original-Sender: ilja.j.honkonen@nasa.gov 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:16328 Archived-At: ------=_Part_3727_95280582.1424185678998 Content-Type: multipart/alternative; boundary="----=_Part_3728_1505424659.1424185678998" ------=_Part_3728_1505424659.1424185678998 Content-Type: text/plain; charset=UTF-8 Hello Regular variables can be written succinctly as constexpr double long_variable_name_1 = 0, long_variable_name_2 = 1, long_variable_name_3 = long_variable_name_1 + long_variable_name_2; instead of constexpr double long_variable_name_1 = 0; constexpr double long_variable_name_2 = 1; constexpr double long_variable_name_3 = long_variable_name_1 + long_variable_name_2; It would be nice to be able to use similar syntax for metavariables, e.g. using long_metavariable_name_1 = int, long_metavariable_name_2 = double, long_metavariable_name_3 = boost::mpl::...; instead of using long_metavariable_name_1 = int; using long_metavariable_name_2 = double; using long_metavariable_name_3 = boost::mpl::...; One could also put template in front of each using word. For more complex cases template using long_metavariable_name_1 = int; template using long_metavariable_name_2 = double; template using long_metavariable_name_3 = boost::mpl::...; the syntax could be using template long_metavariable_name_1 = int, template long_metavariable_name_2 = double, template long_metavariable_name_3 = boost::mpl::...; Shared template parameters could be put in front of the using word above and would be equal to template using long_metavariable_name_1 = int; template using long_metavariable_name_2 = double; template using long_metavariable_name_3 = boost::mpl::...; Is something like this possible? At least it seems to only add new syntax for existing features. Ilja Honkonen -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_3728_1505424659.1424185678998 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hello

Regular variables can be written succinctly a= s
constex= pr = double
    lon= g_variable_name_1 =3D 0= ,
    long_var= iable_name_2 =3D 1,
    long_variable= _name_3
        =3D long_variable_name_1
       = ; += long_variable_na= me_2;
instead of
constexpr double long_variable_name_1 =3D 0= ;
constexpr double long_variable_name_2 =3D 1;
constexpr d= ouble long= _variable_name_3
    =3D long_variable_name_1
    + long_variable_name_2;

I= t would be nice to be able to use similar syntax for metavariables, e.g.
using
   = ; long_metavariable_name_1 =3D int,
  &nbs= p; long_metavariable_name_2 =3D double,<= /span>
  =   long_metavariable_name_3 =3D boost::mpl::= ....;
instead of
using long_metavariable_name_1 =3D int;
u= sing long_= metavariable_name_2 =3D double= ;
using long_metavariable_name_3 =3D boost::mpl::...;
One co= uld also put
template<class= T<= span style=3D"color: #660;" class=3D"styled-by-prettify">>
in front of each using word.

For more complex cases
template<class A> using long_metavariable_name_1 =3D int;<= br>templat= e<class B> using long_metavariable_name_2 =3D double;
template<class C><= span style=3D"color: #000;" class=3D"styled-by-prettify"> using long_metavariable_name_3 =3D boost::mpl::...;
the syntax could= be
using=
 =   te= mplate<= class A> long_metavariable_name_1 =3D int,
    template<class B> long_metavariable_name_2 =3D double,<= br>    template<c= lass C> long_metavariable_n= ame_3 =3D<= /span> boost::mpl::...;
Shared template parameters could be put in front of the using word above = and would be equal to
=
template<class T, class A> using long_metavar= iable_name_1 =3D int;
template<class T, class = B> using long_metavariable_name_2 =3D double;
template<class T, class C> using long_metavariable_name_3 =3D boost::mpl::...;

Is something= like this possible? At least it seems to only add new syntax for existing = features.

Ilja Honkonen

--

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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
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