220 33532 article Path: news.gmane.org!.POSTED!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Catch block for multiple exceptions Date: Wed, 2 Aug 2017 09:38:26 -0400 Lines: 29 Approved: news@gmane.org Message-ID: References: <4126837.jZlGhgVnua@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-Trace: blaine.gmane.org 1501681114 751 195.159.176.226 (2 Aug 2017 13:38:34 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 2 Aug 2017 13:38:34 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 To: std-proposals@isocpp.org, Barry Revzin Original-X-From: std-proposals+bncBC37LBFWUIFBBVNLQ7GAKGQEGAFM6HY@isocpp.org Wed Aug 02 15:38:30 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f197.google.com ([209.85.220.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dctr3-00088J-Kl for gclcip-std-proposals@m.gmane.org; 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[66.194.253.20]) by smtp.googlemail.com with ESMTPSA id o20sm25625456qtc.23.2017.08.02.06.38.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Aug 2017 06:38:27 -0700 (PDT) Original-Newsgroups: gmane.comp.lang.c++.isocpp.proposals In-Reply-To: Content-Language: en-US X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.b=hI9smtNW; spf=pass (google.com: domain of mwoehlke.floss@gmail.com designates 2607:f8b0:400d:c0d::233 as permitted sender) smtp.mailfrom=mwoehlke.floss@gmail.com; dmarc=pass (p=NONE sp=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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:33532 Archived-At: On 2017-08-02 08:47, Barry Revzin wrote: >> And how to know which one invoked? You don't. If you wanted to know if it >> was exceptionA, you'd add a catch block for it. > > You'd almost want something like: > > catch (variant e) { > visit([](auto& e){ f(e); }, e); > } catch (exceptionA, exceptionB, exceptionC e) { if constexpr (std::is_same_type_t) { ...do something with exceptionA... } } IOW, implement such blocks sort of like templates; write the code once, but the compiler internally converts it to separate catch-blocks with the same bodies. -- Matthew -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/d58143f8-c128-3745-b835-1e04a5760d0d%40gmail.com. .