220 33574 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Catch block for multiple exceptions Date: Fri, 4 Aug 2017 03:13:57 +0300 Lines: 49 Approved: news@gmane.org Message-ID: References: <4126837.jZlGhgVnua@tjmaciei-mobl1> <54580edb-4a76-4241-b5c8-19ccbc1a562e@isocpp.org> <4c872807-7d50-4b58-bbb5-595a8bac1246@isocpp.org> 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 1501805642 15337 195.159.176.226 (4 Aug 2017 00:14:02 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 4 Aug 2017 00:14:02 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBR7YR3GAKGQEZ3X3WFQ@isocpp.org Fri Aug 04 02:13:58 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f200.google.com ([209.85.220.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ddQFW-0003bq-2o for gclcip-std-proposals@m.gmane.org; Fri, 04 Aug 2017 02:13:54 +0200 Original-Received: by mail-qk0-f200.google.com with SMTP id s18sf1300320qks.4 for ; Thu, 03 Aug 2017 17:14:00 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1501805640; cv=pass; d=google.com; s=arc-20160816; b=R74iqJcmnU7zw7uEu2Okf2bVp0CIpH7wlUdMboGd9DC8Rl3RzzwOExiFAmmN3wxGMl unTOUKxVZ100wabFPbjQwEUneAJUiTIdJoBxr2gtb8W23ZsqiX3QIpf/iC+ZyOQVSnI2 8UhoLmpN3RdhjI1CWpqKHRTLSr6amV/4qHNdjxdj9Vnsvv8kEp7+hhZlzLufooAwLTRF erxyYPeuUm3GzkqiGAChmIOdcJ7z4rSgFQb9gSbf5fgFkvfPFXSJ8mtaoqxRTLuxblMy iblzqL7L8kXIMU4Uwa8+c2tTCFJpLSvvtLWTdLq7mFJa6codXbDT0uP3XZJDjpmYQrgY bTDQ== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:reply-to:to:subject:message-id:date :from:references:in-reply-to:mime-version:arc-authentication-results :arc-message-signature:dkim-signature:arc-authentication-results; bh=DzY/E3bzfy6tdiFOdl89l9nsM93H/r8EE2TfbfRnPyQ=; b=lZeETFGE/8m7cvMaznR57ErxLtGlIG7EiY9KJaKWJNrA9SqfYbu5hNdr2OtQ602+Zk gtuFR5XVWJMqxTzvw8YAuaTI0v0SV4/cGcR82/0CEosS0pM99uIua4VajcrAvn4ANYoZ so4rHWZH/4EgIco/bzEudE6aEk2VFGr+XVNnk5IAtRZX7yRwB+4BKpRS9zAV7LYf7z7E f3Aie5xl8EWBGs4P8rzoiYYvRIVozV8/rrUyzG8y3kvzCjBNfNGDaMtTnGEKLoe9xBUD xUHUdoBFrHxYDz4NxJgYUmvSRuZkdrHO6F/qPbV/43k8MgO90dPbdxf/m9ddbO/oWnBB Iq9A== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@gmail.com header.b=rnWVaWiv; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c05::244 as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=DzY/E3bzfy6tdiFOdl89l9nsM93H/r8EE2TfbfRnPyQ=; b=buMv29Bz5EL8hTrBzFBv6cBbcw5PRN/QP0Wq0g6CDBPDkcb0pB+GhWuX6sDO4EiPIx ZaC3mPuQiL7J887nmp2Am7riH1fLm8f8zMcjSln9M2Gtx2mnHvyyDTke0mza1Jwkllpc JMAMNJQJJNJg1NHcc58K0GqDpUi3gk8ya7zC0Yyh4rJufKtSQIPSMDRjerUeZa9oevgT JYf7kvSi5R8ACIg7wF4kWtui4qRwhTIVa6IKJUv7CqN/bwzrsIVkNroX0Mt1Dyl7hNid sW4rpcDKCRROAtHV219FTGxZbG2bju1t5BjfKOp3X0wdoYQPO8V/iyl4Zo0GLAGuNpFO bkYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject: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=DzY/E3bzfy6tdiFOdl89l9nsM93H/r8EE2TfbfRnPyQ=; b=HJYjqAZ7E/9VGkNhSY7N4FxajANApEKBOeCsYPx445qcbA9K+fCrV6CvwIJQ+NXiwR GJtyB5vDmIJ0LuW9rNvWcsujvk285ALMDG+u+0pxydyg8UesvuxyioE2iew7jx/3pi70 Vb65oIxX4ovDX5G4lnh3J3SIEXnJ47DJx7vQqj5OK0VJUGMcKMjdAmf7q7ZBc/k1BJeE qPHnItBIjGdzlu8u8O1kPtaJpT8T6JCWcZ91Z2rb7sJ3sMqHB/M5ibp5uHi+ykCrS2zi p3sNHpdg3oEwu7FBz/DMS1f7FieRMziaTlopCbJS80CYMjUPCrD+SQ8LpcPStapR48yz MySA== X-Gm-Message-State: AHYfb5gEkYQOg7ZyoAb1AYMbgEzvAKl+jzjfJUa29RskPwETa5UIo0f6 axNgdeVVHB14vx7x X-Received: by 10.200.54.89 with SMTP id n25mr442384qtb.45.1501805640102; Thu, 03 Aug 2017 17:14:00 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.138.65 with SMTP id v62ls573517itd.3.canary-gmail; Thu, 03 Aug 2017 17:13:58 -0700 (PDT) X-Received: by 10.31.197.133 with SMTP id v127mr384865vkf.12.1501805638861; Thu, 03 Aug 2017 17:13:58 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1501805638; cv=none; d=google.com; s=arc-20160816; b=l6t8qWSpjdbPxT26K/gePvau8WMka6spWqqO8Lk0Qi/zO1snW7Gcsu8TPckirEuf1j HlaA835eAIer0ymMLdjatHVlU/K94J3zjWDkSnAjHcuxyLRrulZAApgAEvLH8OfrLwjX p7bMpAXeuqll3hV4g2nKFmX5JPqFjbFdklsE06c1IqeqrRzKmopIoLzr8AKMmKkXXKtR eRygQ93iE+cAgTGd10uC+edTzH8/ALV0nDdbI+E029sv6pQG3ylS0AxlqteGD7oNlP93 Fv8a8QMzLU+dEjPIZzXuw7wuUM9kzqipwg8pCa/HxptOe8CaKY57O209QtBPyQHm9P14 CHjw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:subject:message-id:date:from:references:in-reply-to:mime-version :dkim-signature:arc-authentication-results; bh=G5pZG9fCckNW0Qn+ETXWwUnaQLh78SHZlVuXsLBkTW8=; b=WZPmw6lDAte6uUWSKaYK66ky9AKFP7fvyLiJKwX/8KmmbYc0zoVNuQ/lurmN9gVANW ZY5b/3GjVXQxB77V/t1BwEt+45jem9xQQ2X3qs4MtZl/yMy2B94rzdo8G6k5YH0Tvumg 0PHEDljhMXB98PAwf7Rrh3JyDFW/53MCAwRMaTliiT6PFfOn83263Lao1+2BU73Qehuz 9BPp2xCtZEolB2B75rMOWfed7rCYW8w+Kavzq/sVNgc2aXVhd3L6+shfY0M8OwhkUWle mzDB9Y71FxIVU2WeSD3YqC+GOVkj8YRpPXiukUMU110fRyWvxci51uXZU1j70PE0zuc9 NKKQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.b=rnWVaWiv; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c05::244 as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gmail.com Original-Received: from mail-vk0-x244.google.com (mail-vk0-x244.google.com. [2607:f8b0:400c:c05::244]) by mx.google.com with ESMTPS id v81si115154vke.343.2017.08.03.17.13.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Aug 2017 17:13:58 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c05::244 as permitted sender) client-ip=2607:f8b0:400c:c05::244; Original-Received: by mail-vk0-x244.google.com with SMTP id d124so109782vkf.1 for ; Thu, 03 Aug 2017 17:13:58 -0700 (PDT) X-Received: by 10.31.238.195 with SMTP id m186mr375604vkh.116.1501805638395; Thu, 03 Aug 2017 17:13:58 -0700 (PDT) Original-Received: by 10.103.103.65 with HTTP; Thu, 3 Aug 2017 17:13:57 -0700 (PDT) In-Reply-To: <4c872807-7d50-4b58-bbb5-595a8bac1246@isocpp.org> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.b=rnWVaWiv; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c05::244 as permitted sender) smtp.mailfrom=ville.voutilainen@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:33574 Archived-At: On 4 August 2017 at 02:17, Arthur O'Dwyer 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? Way to jump the gun. I doubt it, because it doesn't make sense to have one name for different things. However, unerasing the type of an any and an exception_ptr are exactly the same. > Right now we have a different type-un-erasure mechanism for each type-erased > type, and more proliferating with each revision of the Standard: > > std::any a = xx; > assert( std::any_cast(a) == 42 ); > > std::function f = xx; > assert( *f.target() == xx ); > > std::shared_ptr p(new int, xx); > assert( *std::get_deleter(p) == xx ); > > (from > 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 > type-erased types) > > I'm not sure "any_cast" would necessarily be the right spelling, but it is > pretty awkward IMHO that various library designers keep reinventing it over > and over with different spellings. Well, I suppose we could have an unerase(), if you can find enough common functionality, but if you want to make it fully generic, it needs to become a customization point and oh what fun that will be. -- 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/CAFk2RUa2teYd3DAg1VY3xF%3DvCNKUfna4emTSCYLuUa8dw_UmSg%40mail.gmail.com. .