220 27637 <7938962d-5e90-4e0f-b3f2-4f979d314a70@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: inkwizytoryankes@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: this in non-member functions Date: Fri, 5 Aug 2016 11:54:07 -0700 (PDT) Lines: 196 Approved: news@gmane.org Message-ID: <7938962d-5e90-4e0f-b3f2-4f979d314a70@isocpp.org> References: <2351486.cE391vEbrj@tjmaciei-mobl1> <814750ea-1ef8-4792-9b50-aec0bae4d841@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2239_1579967262.1470423247672" X-Trace: blaine.gmane.org 1470423267 4439 195.159.176.226 (5 Aug 2016 18:54:27 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 5 Aug 2016 18:54:27 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDDLTAGNTIBBBUGBSO6QKGQEZ5J5D3Y@isocpp.org Fri Aug 05 20:54:23 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f70.google.com ([209.85.213.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bVkG2-0007AA-Fi for gclcip-std-proposals@m.gmane.org; Fri, 05 Aug 2016 20:54:10 +0200 Original-Received: by mail-vk0-f70.google.com with SMTP id w127sf495438425vkh.1 for ; Fri, 05 Aug 2016 11:54:10 -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 :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=aZLwG9zsSRXQE6uF9W1mXchOyfmmjNBXkhb9xxrKLSA=; b=ShAbbx2EU/yzAyZmny406iyMOEQWWDqlwBPwqgEdtkGQKvL+sl/pFkGHDlfwD1gSZz BJ5yrP8qBnC0NaHR4yBwy1DvkcKuyeQDrbsclpF05WYDoXBTWfN4AsW6c71OOrWRjS4k IUKEIbZERpdQzlXzFZlhOas1e6mIhsZwxXeBK3gC5/YyQFr5YIXznJ4DTnZYzy2cIxlW QYEboH2oSH2N/u9n3TYZ3uUy6GPIh5MseNZaF6TH1oBSonvbF66rUtxCQwLE67ijxcny ruHq4sYl+tTuX4VsQafcBGUTFqsUp7JXOAUot+tFvWkNlFUZoh1XnmVLKBUqjLXuf6CR nWSA== 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 :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=aZLwG9zsSRXQE6uF9W1mXchOyfmmjNBXkhb9xxrKLSA=; b=zsCLmPktxUb2MPBK5fyTIjwxs/jqNBBt3GYvIBC5tA9+Uuxoe4HescImq7lB1RZKr/ E+VGOS81BwuG8sWkbiOgkrBVWTwyCtW3L7tnAGi39y1hV3nOeIs9e9VBv/9E+MJDWpCx +9D0I9JgCnJD6FiWF9/fKW5telro8YyiYlb2/FVT5Xam/zlOLBstUxKkHrhkHnAfDiQy EK7aJjyf2wMYVhJIAbNjlQbXHvdby9xhBK5PIZ4bd8HcZcXjvaPLBgOk91j/qKN4u03c wiw19xl46qxn7mZUecvtuoQGLLEja1LxgLBvKM7NTl4SCNZtuk+McDcD0ICGHhTqq6uy rdLA== 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:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=aZLwG9zsSRXQE6uF9W1mXchOyfmmjNBXkhb9xxrKLSA=; b=TNcx8d1pq3BJhIcXOKGpLbKCcwuEvb1nxi8IdI3TnnGib8097ShcayKNfHX7DHgP2F SFuf5x0jcmTd0vn239d5+BKqgUzKfphcdrBgpV87maZEGiuXgfR8UDYxac5VLTV6eUk5 mHEZxLPEj/lpycWdabsXJx9fvn/5lP4aMPuXcOXrCGspxGeA6SvEzVefig7cvAZwuq1A qDNqe+54gK3TV9MhbSWBPaT/TxlNviVOkBctXrukcS1MIKi2bqLppdULA7hTvuSUfPSm k2TE28eScl9uHGmdbXk8Q82lic6wm7ZfqacTtqUiuGBQgr+giX5Z7ZxQiylhwETiJpCX qtXw== X-Gm-Message-State: AEkoout31510S0MRXL3PiEb5vHrkDfdJ6Yr/nN62NAmPdgDx8Q37pGtc0pyB0LReoCeXZQ== X-Received: by 10.13.217.135 with SMTP id b129mr69204334ywe.13.1470423250418; Fri, 05 Aug 2016 11:54:10 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.18.12 with SMTP id a12ls2632711ioj.18.gmail; Fri, 05 Aug 2016 11:54:08 -0700 (PDT) X-Received: by 10.36.91.205 with SMTP id g196mr230006itb.0.1470423248704; Fri, 05 Aug 2016 11:54:08 -0700 (PDT) In-Reply-To: X-Original-Sender: inkwizytoryankes@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:27637 Archived-At: ------=_Part_2239_1579967262.1470423247672 Content-Type: multipart/alternative; boundary="----=_Part_2240_1672624294.1470423247672" ------=_Part_2240_1672624294.1470423247672 Content-Type: text/plain; charset=UTF-8 On Friday, August 5, 2016 at 7:51:37 PM UTC+2, Viacheslav Usov wrote: > > On Fri, Aug 5, 2016 at 7:17 PM, > > wrote: > > template >> void f(T* this) >> { >> a = 6; >> }; >> What meaning have this code? `a` is member or global value? >> Because member `a` is dependent name compiler need always ignore it and >> go for global with same name. >> This made this proposition unusable in template contexts. >> > > When this is instantiated for a particular type T, then, if there is a > member 'a' in that type, it will mean this->a = 6; if there is no such > member, it will refer to 'a' from an outer scope. Note that at this point I > no longer propose that 'this' could be declared as a regular variable. > Instead, I propose the following form: > > using this = expression; > > Cheers, > V. > But then this will be first time when C++ template quietly change syntax of code when you instantiating different templates, consider this case: class a{}; struct t1 { void f() { a* test; ++test; } }; struct t2 { int a; int test; void f() { a* test; ++test; } }; `t1::f` and `t2::f` look similar but work completely different. How compilers will handle cases when every symbol in function can be member variable? JavaScript had same problems with `with` and solution was to ban it: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/with -- 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/7938962d-5e90-4e0f-b3f2-4f979d314a70%40isocpp.org. ------=_Part_2240_1672624294.1470423247672 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Friday, August 5, 2016 at 7:51:37 PM UTC+2, Via= cheslav Usov wrote:
On Fri, Aug 5, 2016 at 7:17 PM, <inkwizyt...@gmail.com> wrote:

template<typename T>
void f(T* this)
{
=C2=A0 =C2=A0 a =3D 6= ;
};
What meaning have this code? `a` is member or global value?=
Because member `a` is dependent name compiler need always ignore it and= go for global with same name.
This made this proposition unusable in te= mplate contexts.

When this is i= nstantiated for a particular type T, then, if there is a member 'a'= in that type, it will mean this->a =3D 6; if there is no such member, i= t will refer to 'a' from an outer scope. Note that at this point I = no longer propose that 'this' could be declared as a regular variab= le. Instead, I propose the following form:

using t= his =3D expression;

Cheers,
V.
=

But then this will be first time wh= en C++ template quietly change syntax of code when you instantiating differ= ent templates, consider this case:

class a{};=
struct t1
{
= =C2=A0 voi= d f= ()
=C2=A0 {
=C2=A0 =C2=A0 a* test;
=C2=A0 =C2=A0 ++test;
=C2=A0 }
};
struct= t2
{
=C2=A0 int a;
=C2=A0 int test;
=C2=A0 void = f()=
=C2=A0 {
=C2=A0 =C2=A0 a* test;
=C2=A0 =C2=A0 ++test;
=C2=A0 }
};
`t1::f` and `t2::f` look similar but = work completely different. How compilers will handle cases when every symbo= l in function can be member variable?
JavaScript had same problems with = `with` and solution was to ban it: https://developer.mozilla.org/en-US/docs= /Web/JavaScript/Reference/Statements/with


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