220 39392 article Path: news.gmane.org!.POSTED!not-for-mail From: Niall Douglas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Alternative proposal for mapping P0709 Deterministic Exceptions into C Date: Wed, 25 Jul 2018 01:14:33 -0700 (PDT) Lines: 98 Approved: news@gmane.org Message-ID: References: <6a65c934-5d2a-4e75-b88d-9eaaee338bd3@isocpp.org> <1c229827-6d5d-45bd-8766-c3af818b2b0b@isocpp.org> <4ac80882-16fc-4ab4-9a12-64da1ef0e974@isocpp.org> <8866881c-ef1d-4c37-9242-5b1d3327c288@isocpp.org> <363df3db-b747-449f-b95d-81d15b6c3842@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_9700_875305197.1532506473553" X-Trace: blaine.gmane.org 1532506354 3081 195.159.176.226 (25 Jul 2018 08:12:34 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 25 Jul 2018 08:12:34 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDGKFT5YZADRB2XC4DNAKGQEILXSSAA@isocpp.org Wed Jul 25 10:12:30 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f198.google.com ([209.85.161.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fiEuL-0000aL-HF for gclcip-std-proposals@m.gmane.org; Wed, 25 Jul 2018 10:12:29 +0200 Original-Received: by mail-yw0-f198.google.com with SMTP id p127-v6sf3799819ywg.1 for ; Wed, 25 Jul 2018 01:14:40 -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=nY91YSSyptYXwKrn9a9c6IlYh4HHRyqA3qXNVDAajL4=; b=q2ug2gFAVXxTDIjhbyW31Znkd2DDUM5j3jaY2NRICfFmcyoY9AJg/U0iUWBaGPj48o 2cZSZ/y7Dq0EzZtnor5UxvlBSqTggJPxeBcGJh98U05mBRdPx0v2uPNnzbCIq2JFodM0 HDJWy1S5JCm4buNjcWz7/GBX9dh43nLTd3RBYx7E8II0usgnvLSRe9NxbT3A+xlBQQW9 L/AU44SeVNQfS+obBRK6NPKYYWO03wDPfcLnvT4qicq1pd+3VvyFcr7VZQVB90+UtAli pZ55WAz5XgKkcce2HE3WvaXT0fE5zXCd4oSCJ6SxxsG6itOrPVTZovH+atCZWEaePuN/ gFGg== 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=nY91YSSyptYXwKrn9a9c6IlYh4HHRyqA3qXNVDAajL4=; b=XdzCpq0EGATXmiuxcNSFb0yrITvRf6mTiyBqEBUrT0ZJF5LrOmquJFKXl470GalIcs J3ZpREoZsr8qbFc4OGcT5+BcEFhDRmGGWOrzRTCf5F79y85Vqw0OVbBEAtZMmEg9RXda eEskNyQ9ZLGMSn1cET1GKXFZcRHyQEC0pQxbzLH9Fbu/3fIt1ju+GIF5E03MMuMBWTcc kd5q3NJv8i3FXbp2kMHVet2vJvhu8ibntUPT1AOkb8C752LfVOrEjOpiwP3eb8Cgdk6d MQCFFZ7D2veoSTHM5Byl2qLJXhlsmgbllCHfNQac7XUg5+S7TaWmAxHXbBPNrM2EsGLF CRHw== 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=nY91YSSyptYXwKrn9a9c6IlYh4HHRyqA3qXNVDAajL4=; b=GrIm/HrfWu36Jmp01ko/hR0s1XEfpXmGhRAg2pwrTZUGCG3KYcupRcfZ6wQjeDpEaK QmNRPuvDmejm6M8X9MS6qHZMiTfRXpAZAbfeVbc24yHBm1hD3qTzJoClCY1r3bZj+u+5 S+vqnD6BLoWOERtxJw83452L5GkEGDA26rJQhNM38JY79YmO9bYMWHKkcTLVyZCh7XbE 6FgYDZ2lv2FhEq/CO5TWG78zO6Cr34rLyi6mfIzcJrUD3oF5wqKStnYp8Py/XgXgYSxU nvW6avfAzITd6Qmnqjyd0EbUtipddtL5OIqnJiX2xq+dBchBhQvXXdus6co6BHOBlVLn k7Ew== X-Gm-Message-State: AOUpUlEz1E9FirASRpIHfPJEUUamGHaukjlKAh7m1LNezL5k1zJmbwIu IvvW8/4TruvvMP7+y3usxH/B5g== X-Google-Smtp-Source: AAOMgpflp3Ko5Hn4b9lDYEEjfx/yMQDTRODWpXDfSiBYWekAxRJsK5Kv5IccDyoW82S4HXYuq/y53A== X-Received: by 2002:a0d:e486:: with SMTP id n128-v6mr5943830ywe.217.1532506474945; Wed, 25 Jul 2018 01:14:34 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a25:8008:: with SMTP id m8-v6ls3264255ybk.11.gmail; Wed, 25 Jul 2018 01:14:34 -0700 (PDT) X-Received: by 2002:a25:8203:: with SMTP id q3-v6mr340927ybk.1.1532506474054; Wed, 25 Jul 2018 01:14:34 -0700 (PDT) In-Reply-To: <363df3db-b747-449f-b95d-81d15b6c3842@isocpp.org> X-Original-Sender: nialldouglas14@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:39392 Archived-At: ------=_Part_9700_875305197.1532506473553 Content-Type: multipart/alternative; boundary="----=_Part_9701_448495247.1532506473553" ------=_Part_9701_448495247.1532506473553 Content-Type: text/plain; charset="UTF-8" > > >>> It's a C proposal; it doesn't interact with `constexpr`. Indeed, one of >>> its biggest flaws is that it doesn't allow for inter-operation with C++ >>> static exceptions at all, despite being in part based on the same principle. >>> >> >> My _Fails() proposal does however work in constexpr, >> > > `_Fails()` is not valid C++, and `constexpr` is not valid C. How can they > work with one another? Unless you're proposing to add `_Fails()` to C++, > which I think would be a rather hard sell. > I appreciate you are probably not up to date, as I have not issued a new draft of D1095 which incorporates the substantial feedback I received from WG14. And I have only very briefly summarised what will go into that draft on std-proposals and /r/cpp/. But in short, C22 _Fails(T) maps directly onto C++ 23 throws(T). The only difference is auto-propagation, so a _Fails(T) if unhandled results in a failure to compile, whereas a throws(T) if unhandled propagates upwards. This is what WG14 asked for. As C++ 23 would surely be incorporating C22 into itself, whatever goes into C also goes in C++. I intend to propose, in fact, that both mechanisms work perfectly in constexpr. It would let constexpr code choose whether failure should be handled explicitly (_Fails) or implicitly (throws), exactly the same as in non-constexpr. Niall -- 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/ceee4153-dde7-43a3-b43f-aaf62aa01b60%40isocpp.org. ------=_Part_9701_448495247.1532506473553 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

It's a C proposal; it doe= sn't interact with `constexpr`. Indeed, one of its biggest flaws is tha= t it doesn't allow for inter-operation with C++ static exceptions at al= l, despite being in part based on the same principle.

My _Fails() proposal does however work in conste= xpr,

`_Fails()` is not valid C+= +, and `constexpr` is not valid C. How can they work with one another? Unle= ss you're proposing to add `_Fails()` to C++, which I think would be a = rather hard sell.

I appreciate = you are probably not up to date, as I have not issued a new draft of=C2=A0 = D1095 which incorporates the substantial feedback I received from WG14. And= I have only very briefly summarised what will go into that draft on std-pr= oposals and /r/cpp/.

But in short, C22 _Fails(T) m= aps directly onto C++ 23 throws(T). The only difference is auto-propagation= , so a _Fails(T) if unhandled results in a failure to compile, whereas a th= rows(T) if unhandled propagates upwards.

This is w= hat WG14 asked for. As C++ 23 would surely be incorporating C22 into itself= , whatever goes into C also goes in C++. I intend to propose, in fact, that= both mechanisms work perfectly in constexpr. It would let constexpr code c= hoose whether failure should be handled explicitly (_Fails) or implicitly (= throws), exactly the same as in non-constexpr.

Nia= ll

--
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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.
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/ceee4153-dde7-43a3-b43f-aaf62aa01b60= %40isocpp.org.
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