220 31431 <2EDD5373-2876-4B4C-9B68-DFA855DE4007@gmail.com> article Path: news.gmane.org!.POSTED!not-for-mail From: Bryce Glover Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: P0534: call/cc, type safety and exceptions Date: Sat, 4 Mar 2017 20:38:24 -0500 Lines: 204 Approved: news@gmane.org Message-ID: <2EDD5373-2876-4B4C-9B68-DFA855DE4007@gmail.com> References: <26EDCD88-C4FB-47F3-BF21-38D980966CA8@gmail.com> <45450312-284d-3eab-a196-826dedbf0abd@beamways.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_C43991DF-3C34-484D-8B0F-F584F6836B5F" X-Trace: blaine.gmane.org 1488677913 18526 195.159.176.226 (5 Mar 2017 01:38:33 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 5 Mar 2017 01:38:33 +0000 (UTC) Cc: std-proposals@isocpp.org To: Bengt Gustafsson Original-X-From: std-proposals+bncBCPMBF5ZZEBBBFGY5XCQKGQEKSJT4WQ@isocpp.org Sun Mar 05 02:38:27 2017 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 1ckL7v-0003n5-TJ for gclcip-std-proposals@m.gmane.org; Sun, 05 Mar 2017 02:38:24 +0100 Original-Received: by mail-yw0-f198.google.com with SMTP id 203sf244653710ywz.2 for ; Sat, 04 Mar 2017 17:38:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=from:mime-version:subject:in-reply-to:date:cc:message-id:references :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=whxZsApNMsQrmeUxYi61gVF1O7UPPGPl0DAqwL9b8wU=; b=nbopSztMBdBTCZuwuXEqtd8AJa0FEu8Yo2LMV7e2ZM4k9di7gvAzu49O0/AJwRcROH tR8qdJyC0o8gXEbu5HtIdFBJ2r43rT4tzprrWP3GmYC9okc7s5zeWFp6xwPxDbFUqij7 ArOI7ai1iBT1PmjbtaQ1n70qiY2JvSVkH1iGhpmnO5+aeU3XMv9aSdcJOlxefyNN9MOa KCCwdgPgtj0J5sfA1NFUbxL4KpBKpSxpQgLBZmNtsyYmV4EUV24jTj96BqPKM3r61epC 2LntXEKqLOspLiMibYId0e7udsW9drRuyauJ4bwfFS08El4LswhZ+BPN/nA22U3rr+pW Lz4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:mime-version:subject:in-reply-to:date:cc :message-id:references: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=whxZsApNMsQrmeUxYi61gVF1O7UPPGPl0DAqwL9b8wU=; b=g36Rox7SnZCdaDDznIqEAfFUx5icb7v625Jm6xPYJrp86PqnC4HGyXpcV6FOa9hsgo IPBte3FI11LLEQz3FRsVyQUbXpABDZm1k1ZwWZ8O7yB/XFxQ/r5vh+oQbTVw+lTiYnsS 9pnx7vNLmJY5pH+//WivYfIdutLyXduXOtxQpBnQRJeEFUKSQThEWuj5w1RXVgyEmPvy HbMUnRMzRpPpdsqhLKq6EgUW6FBJvSCpIrJeDz8+vYl2LaoAc+4Npo2SDL+3pInwkeO7 9ZbqC7nRlQnX0gO9psoo/V70xBLD8pywDoRxU4q4RSJQpf1+mR2Xdx6m4d1nxds2Z42R eT7A== X-Gm-Message-State: AMke39ngylAfWhe0UDjrYxFcyx5/QadndrRq2rp3wA/qY+uK9WnIVpiuhC2iNa/2BIodWA== X-Received: by 10.129.112.131 with SMTP id l125mr3738434ywc.85.1488677909612; Sat, 04 Mar 2017 17:38:29 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.2.76 with SMTP id 73ls1632974itu.13.gmail; Sat, 04 Mar 2017 17:38:27 -0800 (PST) X-Received: by 10.107.5.213 with SMTP id 204mr8501683iof.189.1488677907898; Sat, 04 Mar 2017 17:38:27 -0800 (PST) Original-Received: from mail-it0-x242.google.com (mail-it0-x242.google.com. [2607:f8b0:4001:c0b::242]) by mx.google.com with ESMTPS id b184si198446iti.119.2017.03.04.17.38.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 04 Mar 2017 17:38:27 -0800 (PST) Received-SPF: pass (google.com: domain of randomdsdevel@gmail.com designates 2607:f8b0:4001:c0b::242 as permitted sender) client-ip=2607:f8b0:4001:c0b::242; Original-Received: by mail-it0-x242.google.com with SMTP id 68so6206433itg.0 for ; Sat, 04 Mar 2017 17:38:27 -0800 (PST) X-Received: by 10.36.208.134 with SMTP id m128mr9391930itg.44.1488677907666; Sat, 04 Mar 2017 17:38:27 -0800 (PST) Original-Received: from [10.0.1.11] (c-68-50-177-220.hsd1.in.comcast.net. [68.50.177.220]) by smtp.gmail.com with ESMTPSA id m125sm6481234iom.38.2017.03.04.17.38.26 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sat, 04 Mar 2017 17:38:26 -0800 (PST) In-Reply-To: <45450312-284d-3eab-a196-826dedbf0abd@beamways.com> X-Mailer: Apple Mail (2.3124) X-Original-Sender: RandomDSdevel@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of randomdsdevel@gmail.com designates 2607:f8b0:4001:c0b::242 as permitted sender) smtp.mailfrom=randomdsdevel@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:31431 Archived-At: --Apple-Mail=_C43991DF-3C34-484D-8B0F-F584F6836B5F Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On Mar 3, 2017, at 7:36 AM, Bengt Gustafsson wrote: > I don't know what you mean by trampoline in this context. I checked wikip= edia link but I didn't get it... >=20 > =E2=80=A6 Yeah, sorry, that article=E2=80=99s not as descriptive as one would ho= pe, is it? Maybe this StackOverflow question will help you understand what = I was trying to convey, or perhaps I was just confusing the idea of a tramp= oline with the similar concepts of thunks and/or shims . The ex= ample I usually tend to think of is the Objective-C run-time library=E2=80= =99s `objc_msgSend()` function (which I=E2=80=99ve found is referred to as a trampoline) due to my rudimentary= familiarity with Apple platforms, but I=E2=80=99m not sure how helpful tha= t might be to you=E2=80=A6 > =E2=80=A6 >=20 > This aside, do you see a reason for this being a tag type and operator() = rather than a method call? >=20 > =E2=80=A6 Honestly, I don=E2=80=99t have enough of an opinion on or enough stake in t= his argument to care all that much either way. I just see continuations as= an interesting construct that I might use some time in the future. =20 > =E2=80=A6 >=20 > I thought about this more and it seems that it may have to do with implem= enting a fiber pool. The invoked function is the body of the next fiber to = execute on the stack of the continuation and the target of the ccllcc is ju= st a function like this: >=20 > void fiber_base(continuation&& cont, bool& stop) > { > continuation c =3D std::move(cont); > while (!stop) > c =3D c(); > } >=20 > then the party starting the fiber_base with callcc can invoke anything on= this stack and when this anything returns the loop goes back to wait for t= he next task. >=20 > This idea is just speculation on my part, but it seems to show a use case= (unless the stack itself is made a first class object which can be reused = for multiple callcc calls which I would find more logical).=20 >=20 > =E2=80=A6 That=E2=80=99s another way of looking at it, I suppose=E2=80=A6 =E2=80=94=E2=80=89Bryce Glover =E3=80=80=E2=80=89RandomDSdevel@gmail.com > =E2=80=A6 >=20 > Den 2017-03-02 kl. 23:21, skrev Bryce Glover: >> (snipped=E2=80=A6) > --=20 > Bengt Gustafsson > CEO, Beamways AB > Westmansgatan 37 > 582 16 Link=C3=B6ping, Sweden > +46 (705) 338259 > Skype: benke_g > www.beamways.com --=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/2EDD5373-2876-4B4C-9B68-DFA855DE4007%40gmail.com= .. --Apple-Mail=_C43991DF-3C34-484D-8B0F-F584F6836B5F Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On Mar 3, 2017, at 7:36 AM, Bengt G= ustafsson <b= engt.gustafsson@beamways.com> wrote:
=20 =20

I don'= t know what you mean by trampoline in this context. I checked wikipedia link but I didn't get it...

=E2= =80=A6

  =    Yeah, sorry, that article=E2=80=99s not as descriptive as one = would hope, is it?  Maybe this StackOverflow = question will help you understand what I was trying to convey, or = perhaps I was just confusing the idea of a trampoline with the similar conc= epts of thu= nks and/or shims.  The example I usually tend to think of= is the Objective-C run-time library=E2=80=99s `objc_msgSend()` function (w= hich I=E2=80=99ve found is referred to as a trampoline) due= to my rudimentary familiarity with Apple platforms, but I=E2=80=99m not su= re how helpful that might be to you=E2=80=A6

=E2=80=A6

This aside, do you see a reason for this being a tag type and operator() rather than a method call?

=E2=80=A6

Hon= estly, I don=E2=80=99t have enough of an opinion on or enough stake in this= argument to care all that much either way.  I just see continuations = as an interesting construct that I might use some time in the future.  = ;

=E2= =80=A6

I thought about this more and= it seems that it may have to do with implementing a fiber pool. The invoked function is the body of the next fiber to execute on the stack of the continuation and the target of the ccllcc is just a function like this:

void fiber_base(continuation&& cont, bool&= amp; stop)
{
<= blockquote type=3D"cite" class=3D"">    continuation c =3D std::m= ove(cont);
   w= hile (!stop)
   = ;    c =3D c();
= }

then the party starting the fiber_= base with callcc can invoke anything on this stack and when this anything returns the loop goes back to wait for the next task.

This idea is just speculation on my part, but it seems to show a use case (unless the stack itself is made a first class object which can be reused for multiple callcc calls which I would find more logical). 

=E2= =80=A6

That=E2=80=99s anot= her way of looking at it, I suppose=E2=80=A6

=E2=80=94=E2=80=89Bryce Glover
= =E3=80=80=E2=80=89Ran= domDSdevel@gmail.com

=E2=80=A6

Den 2017-03-02 kl. 23:21, skrev Bryce Glover:
(snipped=E2=80=A6)
--=20
Bengt Gustafsson
CEO, Beamways AB
Westmansgatan 37
582 16 Link=C3=B6ping, Sweden
+46 (705) 338259
Skype: benke_g
www=
..beamways.com

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