220 33572 <4c872807-7d50-4b58-bbb5-595a8bac1246@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Arthur O'Dwyer Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Catch block for multiple exceptions Date: Thu, 3 Aug 2017 16:17:43 -0700 (PDT) Lines: 331 Approved: news@gmane.org Message-ID: <4c872807-7d50-4b58-bbb5-595a8bac1246@isocpp.org> References: <4126837.jZlGhgVnua@tjmaciei-mobl1> <54580edb-4a76-4241-b5c8-19ccbc1a562e@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_295_1335713273.1501802263600" X-Trace: blaine.gmane.org 1501802269 1221 195.159.176.226 (3 Aug 2017 23:17:49 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 3 Aug 2017 23:17:49 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDLZJYWNDQIJRXUOZQCRUBCZZVKQC@isocpp.org Fri Aug 04 01:17:44 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-io0-f198.google.com ([209.85.223.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ddPN6-0008E2-B8 for gclcip-std-proposals@m.gmane.org; Fri, 04 Aug 2017 01:17:40 +0200 Original-Received: by mail-io0-f198.google.com with SMTP id h70sf870945ioi.14 for ; Thu, 03 Aug 2017 16:17:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; 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; bh=gLMqKh8LdYaLLFKiOden1vZ5BC8DcasgoUsauaz7rXg=; b=FO7RXDUHI4nzeDQArvu1j+kQrNg43GIY/thoxe6qu4xJzB2g8G2WplMIB6F36Rl8qG A6aCYnVTWjxZhpGBM0AeG0jT51Nj+qJdntGvo5d9qTgwlCiA9+k/4jNhyhMhTuAioDSB UCJ3YGxBBfPkW0McS2rh/l3hjP+5khe6DRCvAiB/eCvULYY6zpOcGN8hSYxK51WH7fvC UA/zF9Yo10MSXThrnwkCghHNuPT0+I0CQZXJgMDsTKR1ZQubyKRNixRL3eu64OJ4CSHT 9DyA9DVEIABWGhwttCXAVFwY7V3eDUsPSJENV6hCT2sxKTKKhL3wrm6wegFT1d9M+y1m vCSQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; 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; bh=gLMqKh8LdYaLLFKiOden1vZ5BC8DcasgoUsauaz7rXg=; b=YrPT32GpvvUnTZtnII2gOQCE2Unls8HfiJgJ+Q1YigUumVgErXHsB5k2E3nC2tN5+g lxTNxwfcVTk+aIYsJAVteRFoua6mVA7NafxV2mHk+whk3WDRDdY/q469G2dddjHm3VPz JdG1ieHA+BsK6wA05SccG+fO7Mb//+nflnk7WZ5ccvFXS1AcBDPFljfouqtLTXj5sUEQ ej/6Bx95LfbNi7rI1lWHQMLu2E5HXxXBPnwldObyQS00xspJ2dHDs/tJksbNmAhKEhhW KSv++OgIgLpdIIznZWXxa5BUXCFBO0cSuT19uCqODo1qx93rCZzxauAPWLqFstr8+jVm 8mmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; 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:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=gLMqKh8LdYaLLFKiOden1vZ5BC8DcasgoUsauaz7rXg=; b=jYLDdVZKn114ZFbnC/kwV+zkw65kyJf8RWNWtjwqmdXHNSVN4/7M5TK1a9IC2ha4px JgMrVv8ZJzeKEFkMZWgN2+u3W8Br1V2ntDdBj0FShJvkS4Gy4gToHBYSwo0gHdfED9Fo 89qQGY3DcSU5B/mM5ByPbkPViM5dL4RoHS2dG843b7HM6H9++5+WH1uCj3YxsQPukROc 2F+UKXobaZ0oZC/IXVGATiCbEr897AsXMVbowGzWPlG8jbN8GDIXsTNKTqfY4z5VJ2CO B2uIeL+g7IYgL35fqPs7cICW0ix0FXFrQ0YTfNSvihXto+VThlJeGwCRcxnPZ4aQPz3f Xjsw== X-Gm-Message-State: AIVw1121g84nZl6bzwSBCLocbYo+J4WzNsIzjZ390dVAbS0hURBKW/4f R04KpWuuYV9D9ivg X-Received: by 10.36.34.149 with SMTP id o143mr151875ito.29.1501802265801; Thu, 03 Aug 2017 16:17:45 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.138.134 with SMTP id v128ls570569itd.15.gmail; Thu, 03 Aug 2017 16:17:44 -0700 (PDT) X-Received: by 10.31.191.67 with SMTP id p64mr2487vkf.4.1501802264282; Thu, 03 Aug 2017 16:17:44 -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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:33572 Archived-At: ------=_Part_295_1335713273.1501802263600 Content-Type: multipart/alternative; boundary="----=_Part_296_2103261817.1501802263600" ------=_Part_296_2103261817.1501802263600 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wednesday, August 2, 2017 at 4:38:01 PM UTC-7, Ville Voutilainen wrote: > > > Note that both of our solutions suffer from the problem that the code=20 > in the catch-clause=20 > cannot break, continue, goto or return like plain code could. An=20 > if-else chain of any_casts=20 > from exception_ptr would be able to do that.=20 > Do you think LEWG would be amenable to a proposal to make std::any_cast an= =20 all-purpose "type-un-erasing" mechanism in C++2a? Right now we have a different type-un-erasure mechanism for each=20 type-erased type, and more proliferating with each revision of the Standard= : std::any a =3D xx;assert( std::any_cast(a) =3D=3D 42 ); std::function f =3D xx;assert( *f.target() =3D=3D xx ); std::shared_ptr p(new int, xx);assert( *std::get_deleter(p) =3D= =3D xx ); (from=20 https://stackoverflow.com/questions/44788017/retrieve-typeid-of-shared-ptr-= deleter ) (and from this thread, we can add std::exception_ptr to the list of=20 type-erased types) I'm not sure "any_cast" would necessarily be the right spelling, but it is= =20 pretty awkward IMHO that various library designers keep reinventing it over= =20 and over with different spellings. =E2=80=93Arthur --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/4c872807-7d50-4b58-bbb5-595a8bac1246%40isocpp.or= g. ------=_Part_296_2103261817.1501802263600 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Wednesday, August 2, 2017 at 4:38:01 PM UTC-7, Ville Vo= utilainen wrote:

Note that both of our solutions suffer from the problem that the code
in the catch-clause
cannot break, continue, goto or return like plain code could. An
if-else chain of any_casts
from exception_ptr would be able to do that.

Do you think LEWG would be amenable to= a proposal to make std::any_cast an all-purpose "type-un-erasing"= ; mechanism in C++2a?
Right now we have a different type-un-erasu= re mechanism for each type-erased type, and more proliferating with each re= vision of the Standard:

s=
td::any a =3D xx;
assert( std::any_cast<Type>(a) =3D=3D 42=
 );

std::function<=
long()> f =3D xx;
assert( *f.target=
<Type>() =3D=3D xx );<=
/span>

std::shared_ptr<int&g=
t; p(new int, xx=
);
assert( *std::get_delete=
r<Type>(p) =3D=
=3D xx );
(and from this thread, we= can add std::exception_ptr to the list of type-erased types)
I'm not sure "any_cast" would necessarily be the = right spelling, but it is pretty awkward IMHO that various library designer= s keep reinventing it over and over with different spellings.
=E2=80=93Arthur

--
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/4c872807-7d50-4b58-bbb5-595a8bac1246= %40isocpp.org.
------=_Part_296_2103261817.1501802263600-- ------=_Part_295_1335713273.1501802263600-- .