220 22001 article Path: news.gmane.org!not-for-mail From: Oliver Kowalke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: is await an extension of the do-notation? (was Re: Re: Resumable expressions p0114r0 vs async/await P0057R0) Date: Tue, 27 Oct 2015 07:47:41 +0100 Lines: 162 Approved: news@gmane.org Message-ID: References: <639f0012-8cb4-4db3-82a6-8d042a3497f9@isocpp.org> <401aa118-ed0b-4c7b-92cf-3fbd706eff9d@isocpp.org> <1d15dbc4-e0c1-4df1-86db-014e11f14d26@isocpp.org> <56114953.4030701@wanadoo.fr> <561B403D.4030403@gmail.com> <561C07D1.3080304@gmail.com> <561C213F.1060009@gmail.com> <561C3875.2050701@gmail.com> <86924069-44d0-447f-bf8a-a42e46579832@isocpp.org> <561D79A7.8080007@gmail.com> <894616d6-9609-4038-b2bc-d2c62df21e0f@isocpp.org> <99bdb3ae-9214-4440-8572-4c47a61eda46@isocpp.org> <58628096-14ae-42b2-89d3-c0bd2183bbc0@isocpp.org> <561DC957.8080603@gmail.com> <2e09660f-d688-474a-8811-85fb041f68b8@isocpp.org> <8b78abb4-16b6-4b65-8513-6e2c17317647@isocpp.org> <779be861-3b2a-427a-b36b-ad2874c81129@isocpp.org> <767364f8-785d-4f8f-9bc0-852df56ee4eb@isocpp.org> <0a728eee-e8e7-48ea-adf6-2a8dae63916e@isocpp.org> <6a4f863e-faf0-42ac-b85d-0951738350ab@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a1140978c7c8482052310755a X-Trace: ger.gmane.org 1445928484 23679 80.91.229.3 (27 Oct 2015 06:48:04 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 27 Oct 2015 06:48:04 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCLZHP5J7MHRBIN4XSYQKGQEVY5DRBI@isocpp.org Tue Oct 27 07:48:04 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yk0-f198.google.com ([209.85.160.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Zqy39-0003m4-2b for gclcip-std-proposals@m.gmane.org; Tue, 27 Oct 2015 07:48:03 +0100 Original-Received: by ykdr3 with SMTP id r3sf341656855ykd.2 for ; Mon, 26 Oct 2015 23:48:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type: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=540TTbo+DsLsT3vTJjEav6zvreO3nw1E9z31ycp+I7E=; b=bovxR3WyRGS54wGVwTLhiLmZUrkNuNs1taHaMCIk/sD0IzHT7cqpdgpNjgB9oerTFQ LuU8p9l9eti5cEgl46k2uyN43kgzrUklZ8q8T47dVLcRa2NMSynOJpp4a35SUv2i649B EC/KT7tSKNSIuWP+pIL9BwaOZDOjv0AopIOCRb2JCKxUNVpSdA9khVKsCh7+pki4DcKV 7RtL5kMG10SSesU/4k3z2tcCNOkb/90D3oav2nysrBV4sOeWwAo5HMG0AwILC2WO5SE2 6/djxTxKCXWFsqtu5bzWRXSHE+IC4NRzwmcQD/XIBcapuN+mRbDf3z4PQzuTXhyJEgTC nBmg== X-Gm-Message-State: ALoCoQliCJSKeeGFT4EiMMRZ/OY8Cpt3R4S2RuREbuUyi9PPUHoz2ufnN8kmKRf8EzPkk567616h X-Received: by 10.13.232.148 with SMTP id r142mr9430195ywe.51.1445928482339; Mon, 26 Oct 2015 23:48:02 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.248.129 with SMTP id ym1ls1956038obc.25.gmail; Mon, 26 Oct 2015 23:48:01 -0700 (PDT) X-Received: by 10.60.23.1 with SMTP id i1mr26623268oef.57.1445928481271; Mon, 26 Oct 2015 23:48:01 -0700 (PDT) Original-Received: from mail-oi0-x231.google.com (mail-oi0-x231.google.com. [2607:f8b0:4003:c06::231]) by mx.google.com with ESMTPS id et5si12928228obb.104.2015.10.26.23.48.01 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Oct 2015 23:48:01 -0700 (PDT) Received-SPF: pass (google.com: domain of oliver.kowalke@gmail.com designates 2607:f8b0:4003:c06::231 as permitted sender) client-ip=2607:f8b0:4003:c06::231; Original-Received: by oiao187 with SMTP id o187so114492468oia.3 for ; Mon, 26 Oct 2015 23:48:01 -0700 (PDT) X-Received: by 10.202.104.201 with SMTP id o70mr26141631oik.126.1445928481095; Mon, 26 Oct 2015 23:48:01 -0700 (PDT) Original-Received: by 10.76.23.231 with HTTP; Mon, 26 Oct 2015 23:47:41 -0700 (PDT) In-Reply-To: <6a4f863e-faf0-42ac-b85d-0951738350ab@isocpp.org> X-Original-Sender: oliver.kowalke@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of oliver.kowalke@gmail.com designates 2607:f8b0:4003:c06::231 as permitted sender) smtp.mailfrom=oliver.kowalke@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=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-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:22001 Archived-At: --001a1140978c7c8482052310755a Content-Type: text/plain; charset=UTF-8 2015-10-22 14:47 GMT+02:00 Giovanni Piero Deretta : > template > class context; > > template > context::context() ; // create any empty context > > template > context::context( Fn && fn, Args && ... args); // requires > IsSame, args..), context>; > > template > R context::operator()(T); // invokes context and implicitly pass to it > this context. On return 'this' contains the context we are coming from. > Returning it explicitly is an alternative. > I believe that this API might only work for asymmetric context switching: void bar( context synthctx2) { synthctx(); } void foo( context synthctx1) { context ctx2( bar); ctx2(); } context ctx1( foo); ctx1(); context 'ctx1' and 'ctx2' own a side-stack 'synthctx1' and 'synthctx2' are synthesized context' (ctor of 'ctx1' and 'ctx2') passed as argument to 'foo() / 'bar()' 'synthctx1' is used to switch back to 'foo' (re-enter context ctx1), but it does not own (or has a connection to) the side stack managed by 'ctx1'! in the ctor of 'ctx2' we have not access to the control structure managing the side-stack of 'ctx1' 'synthctx1' is not equivalent to 'ctx1' but of the same type - that foolish the user another variation of the API; the current active context is passed as an argument (no static pointer) to the context-fn: context( Fn && fn, Args && ... args); // Fn signature '(context, void *)' static context main_context(); void * operator()( context from, void * data); ctor creates and owns side-stack 'operator()' requires the context to be resumed (+ data transferred to it) and we can shared the ownership of side-stack with the synthesized context. the API requires static member function 'main_context()' because in 'main()' (or in top-level std::thread-fn) we don't have a context at hand from which we switch to our desired context. in order to be equivalent to the semantics of the other context', 'main_context()' returns a context that refers to the same type (maybe allocated using 'schwarz pointers' etc.) void bar( context currctx2, void * vp) { context mctx = ( context *) vp; ( * mctx)( currctx2); } void foo( context currctx1, void * vp) { context ctx2( bar); ctx2( currctx1, vp); } context mctx = context::main_context(); context ctx1( foo); ctx1( mctx, & mctx); -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. --001a1140978c7c8482052310755a Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
2015= -10-22 14:47 GMT+02:00 Giovanni Piero Deretta <gpderetta@gmail.com&g= t;:
template<= ;class T, class R>
class context;

template<class T, cl= ass R>
context::context() ; // create any empty context

templa= te<class T, class R>
context::context( Fn && fn, Args &= ;& ... args); // requires IsSame<result_of<Fn(context<R,T>,= args..), context>;

template<class T, class R>
R context= ::operator()(T); // invokes context and implicitly pass to it this context.= On return 'this' contains the context we are coming from. Returnin= g it explicitly is an alternative.

I believe that this API might only work for asymmetric context switching:=

void bar( context synthctx2) {
=C2=A0=C2= =A0 synthctx();
}

void foo( context synthct= x1) {
=C2=A0=C2=A0 context ctx2( bar);
=C2=A0= =C2=A0 ctx2();
}

context ctx1( foo);
ctx= 1();

context 'ctx1' and 'ctx2'= ; own a side-stack
'synthctx1' = and 'synthctx2' are synthesized context' (ctor of 'ctx1'= ; and 'ctx2') passed as argument to 'foo() / 'bar()'
'synthctx1' is used to switch bac= k to 'foo' (re-enter context ctx1), but it does not own (or has a c= onnection to) the side stack
managed by= 'ctx1'!
in the ctor of 'ct= x2' we have not access to the control structure managing the side-stack= of 'ctx1'
'synthctx1' is not equivalent to 'ctx1= 9; but of the same type - that foolish the user

another variation of the API; the current active context is pa= ssed as an argument (no static pointer) to the context-fn:

context( = Fn && fn, Args && ... args); // Fn signature '(context,= void *)'
static context main_conte= xt();
void * operator()( context from, = void * data);

ctor creates and owns= side-stack
'operator()' requir= es the context to be resumed (+ data transferred to it) and we can shared t= he ownership
of side-stack with the syn= thesized context.

the API requires = static member function 'main_context()' because in 'main()'= (or in top-level std::thread-fn)
we do= n't have a context at hand from which we switch to our desired context.=
in order to be equivalent to the seman= tics of the other context', 'main_context()' returns a context = that refers to
the same type (maybe all= ocated using 'schwarz pointers' etc.)

void bar( contex= t currctx2, void * vp) {
=C2=A0=C2=A0 context mctx =3D ( context *) vp;<= br>
=C2=A0=C2=A0 ( * mctx)( currctx2);
}

void foo( context currctx1, void * vp) {
=C2=A0=C2=A0= context ctx2( bar);
=C2=A0=C2=A0 ctx2( currctx1, vp);
}
context mctx =3D context::main_context();
co= ntext ctx1( foo);
ctx1( mctx, & mctx);

--

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