220 14282 article Path: news.gmane.org!not-for-mail From: Giovanni Piero Deretta Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: comment on n4244 Date: Tue, 28 Oct 2014 07:00:25 -0700 (PDT) Lines: 83 Approved: news@gmane.org Message-ID: References: <5d78c59b-4d67-45f6-9d99-8c4beeeac055@isocpp.org> <5344687e-e1de-4205-885c-b5c2f9580129@isocpp.org> <187da710-8adc-4516-bf64-263951503bc7@isocpp.org> <42ddf641-27c7-42a5-ab1c-772667797e5b@isocpp.org> <05a08ac6-f9b8-4ebb-9cb8-9a37a6fd4527@isocpp.org> <3ff7fe35-37c6-4f95-8701-1798b0112c10@isocpp.org> <934c6ace-40cc-484a-96ea-b05aff88482d@isocpp.org> <1d0b64d1-ca4b-448a-9589-01fdc0b85d55@isocpp.org> <804b06d1-9c63-4ef2-a3e8-ccfbdae30ebf@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_1371_1794402965.1414504825296" X-Trace: ger.gmane.org 1414504834 29345 80.91.229.3 (28 Oct 2014 14:00:34 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 28 Oct 2014 14:00:34 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDEP3I7TGEIPVQV6UICRUBE2MXLJI@isocpp.org Tue Oct 28 15:00:28 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f197.google.com ([209.85.213.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xj7Jz-0001TX-8W for gclcip-std-proposals@m.gmane.org; Tue, 28 Oct 2014 15:00:27 +0100 Original-Received: by mail-ig0-f197.google.com with SMTP id r10sf4978498igi.8 for ; Tue, 28 Oct 2014 07:00:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; 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 :content-type; bh=W4rLIgCWwK2oG926b3dmShfJB/IeHMKprzaBGUqTFWo=; b=mGqS9/LjZN2tq/9S83C9bw5MIVGQPDFU1dnj4H/VuQo8Ad1dNK3OyIaA6HqF3x4vce 0KQ3JflZplTmrjH9GiXyAGG9RLttg859JbWNHztL6mfg7OT0pfaU7m91TSpbznyO3yBD D3JrfwzvLkQ/ZyhJMhEvwwDATcmNlxYt1EbPllFbJAB2osZs4klxBXCDuzW3ZNsfXvdU UWEt92vKONj/Bup2yNubLxCHdHXsRSbt86egs/vHxl2b1otLFubQX9RpvrT1l1yDOwBL twH/G/9qjkP4MDh17q3RG29XM/98bdSynRGVuRYxPimP9cANWRvkCU3uD3+kMf720nxD T08g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=W4rLIgCWwK2oG926b3dmShfJB/IeHMKprzaBGUqTFWo=; b=YCbpytup1j5qbMpcIeR7w+tozP22KaQ1E98c9NLy/aa59U6OwfUciD5b/IygGYjQEC 6jZDmvCMDUlGTxmLZl6C42cif/zT8OJI+oisoEfT+7xPlGb+s00h581QFtrn0Q+OxzPz MhiScTRlL7aHU+WDaBXL5gr7Ifc/Qf+b6tB08PKtYxn1FtmKRTsnAg7A7gXuUj6yYmmr Wlx9ZyxkK3QKZA1UK06kh6z/qXXFUCA+Lq2NsyaKEqOHc00qFyGeNpXCC6L0rQtvOrdw tBdJriPKBE8KRywPuB6eA0WI8unl/Wow+AhoLimCY9aHhAPcFETqhJq4ZUzXZGqx8VuN PDMQ== X-Gm-Message-State: ALoCoQkc1fs7AWt09xlOFmXX+Rh0ph4u/YCZOmNDzajZNuJAvgO7fidNJCebjU6ecgoOGxAJURv7 X-Received: by 10.43.35.205 with SMTP id sx13mr2953833icb.1.1414504826620; Tue, 28 Oct 2014 07:00:26 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.43.100 with SMTP id d91ls230468qga.6.gmail; Tue, 28 Oct 2014 07:00:26 -0700 (PDT) X-Received: by 10.140.39.85 with SMTP id u79mr10399qgu.16.1414504826065; Tue, 28 Oct 2014 07:00:26 -0700 (PDT) In-Reply-To: <804b06d1-9c63-4ef2-a3e8-ccfbdae30ebf@isocpp.org> X-Original-Sender: gpderetta@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:14282 Archived-At: ------=_Part_1371_1794402965.1414504825296 Content-Type: text/plain; charset=UTF-8 On Tuesday, October 28, 2014 1:24:20 PM UTC, Gor Nishanov wrote: > > > >> >> why would they be not safe? They are perfectly safe in N4244 design. As >> safe as the rest of the c++ at least. >> > > Notice that lambda* transforms the variables form the body of operator()() > in a member variable of the class. Aliases may appear without you noticing; > > std::string s = "hello"; > for(ch: S) yield ch; > > hargh, that's pretty damning. You do not even need the string: char s[] = "hello"; for(ch: S) yield ch; for this specific case the compiler *could* fix the iterator, but you can come up with other cases in which it is unfeasible. I agree that making generator copyable by default would be terribly error prone. There might be a way out that might satisfy everybody's requirements. Let me think about it. -- --- 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. 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On Tuesday, October 28, 2014 1:24:20 PM UTC, Gor N= ishanov wrote:
 
 
why woul= d they be not safe? They are perfectly safe in N4244 design.  As safe = as the rest of the c++ at least.

Notice that lambda* transforms the variables form the body of operator()(= ) in a member variable of the class. Aliases may appear without you noticin= g;

std::string s =3D "hello";
for(ch: S)= yield ch;


hargh, that's pr= etty damning. You do not even need the string:
 
  cha= r s[] =3D "hello";
  for(ch: S) yield ch;

for = this specific case the compiler *could* fix the iterator, but you can come = up with other cases in which it is unfeasible. I agree that making generato= r copyable by default would be terribly error prone.

The= re might be a way out that might satisfy everybody's requirements. Let me t= hink about it.

--

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