220 14195 article Path: news.gmane.org!not-for-mail From: =?UTF-8?Q?Klaim_=2D_Jo=C3=ABl_Lamotte?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Templetized namespaces Date: Fri, 24 Oct 2014 13:48:04 +0200 Lines: 303 Approved: news@gmane.org Message-ID: References: <4cfc2db6-97da-4750-9296-5aaaa3475014@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a1139761cfe7aa7050629c0f2 X-Trace: ger.gmane.org 1414151293 22110 80.91.229.3 (24 Oct 2014 11:48:13 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 24 Oct 2014 11:48:13 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD3NR2WQQ4IBB5XYVCRAKGQEN6JLSLY@isocpp.org Fri Oct 24 13:48:09 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f70.google.com ([209.85.192.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XhdLk-0006E2-EH for gclcip-std-proposals@m.gmane.org; Fri, 24 Oct 2014 13:48:08 +0200 Original-Received: by mail-qg0-f70.google.com with SMTP id a108sf2404037qge.5 for ; Fri, 24 Oct 2014 04:48:07 -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:date :message-id:subject:from:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=16sAD+g8RoNgbEpJju6YZJx+aES9CeTFU/hkbYRh6hk=; b=Ul0mEquMpT8ob5pXZm37lHLrjJsCkV1OW5dIYuCjjjaTnjJvi8equYlfCX89wU7GkH 6AGhJoS0aC5D2aMuHhn2DPZ8OWVS3FamweM8omw65uWR1up0DjNayhmwm8E2hiScBrwa EUioSeAAK+GCCnkqYzT/FKd4q0eeHmdDvJOvK0AFtv0kTQc9obtBHxauCFkQP/jLtAt+ KTNKzdlpttLUVeuTq6cajvl+M7ndJnNbOeEyA1Tfkuxi8w0lshI4kygMu3ED2Up3P4Q2 tiwBVSH/LjGzQsLPj6AXlEzmtMlaeU/rJDX8esH62PxnyG/i1TlPiN0tc/f3Z8jExtuD 2aVA== X-Gm-Message-State: ALoCoQnZxO9342inj9bxqfepEUXvUupZ8h/i4F/L8aTF7SgnnfLsiBHNuWObUFUILAuutK8gMzR6 X-Received: by 10.236.70.137 with SMTP id p9mr7117641yhd.45.1414151287173; Fri, 24 Oct 2014 04:48:07 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.80.213 with SMTP id c79ls1686509qgd.56.gmail; Fri, 24 Oct 2014 04:48:06 -0700 (PDT) X-Received: by 10.236.230.40 with SMTP id i38mr4441072yhq.34.1414151286638; Fri, 24 Oct 2014 04:48:06 -0700 (PDT) Original-Received: from mail-yh0-x22d.google.com (mail-yh0-x22d.google.com. [2607:f8b0:4002:c01::22d]) by mx.google.com with ESMTPS id v44si4972336yhv.201.2014.10.24.04.48.06 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 24 Oct 2014 04:48:06 -0700 (PDT) Received-SPF: pass (google.com: domain of mjklaim@gmail.com designates 2607:f8b0:4002:c01::22d as permitted sender) client-ip=2607:f8b0:4002:c01::22d; Original-Received: by mail-yh0-f45.google.com with SMTP id f73so349908yha.32 for ; Fri, 24 Oct 2014 04:48:06 -0700 (PDT) X-Received: by 10.170.58.2 with SMTP id a2mr5969694yka.78.1414151284879; Fri, 24 Oct 2014 04:48:04 -0700 (PDT) Original-Received: by 10.76.132.136 with HTTP; Fri, 24 Oct 2014 04:48:04 -0700 (PDT) In-Reply-To: X-Original-Sender: mjklaim@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of mjklaim@gmail.com designates 2607:f8b0:4002:c01::22d as permitted sender) smtp.mail=mjklaim@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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:14195 Archived-At: --001a1139761cfe7aa7050629c0f2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sorry I didn't see your reply before. On Sun, Jan 26, 2014 at 1:52 AM, dgutson . wrote: > On Wed, Jan 22, 2014 at 9:47 AM, Klaim - Jo=C3=ABl Lamotte > wrote: > >> I had the exact same ideas few months ago after finding myself doing >> generic library which all types would depend on the same type, >> and remarking how much duplication could be avoided if I was allowed to >> specify that a whole bunch of types would automatically have an addition= al >> template parameter implicitly. >> >> namespace blah< typename X > >> { >> class K {}; >> template < class T > class U {}; >> } >> >> would be translated to >> >> namespace blah >> { >> template< typename X > >> class K {}; >> template< typename X, class T > class U {}; >> } >> >> >> However, after weeks of thinking about this I concluded that: >> >> 1. namespace are not the appropriate construct for this, they really ar= e >> too different and not really encapsulating anything than names; >> 2. there are a lot of potential issues related to the order of template >> arguments; >> > > Please elaborate about the last two points. > > Basically, namespaces don't have a unique definition and are only affecting naming. Therefore, what would be better to template would be something like a module or a class or a mixin (a class component). > 3. there is a potential issue for reading the code as you need to see >> the namespace declaration before being able to follow the rest of the co= de. >> > > I don't find this issue different than any other template declaration, fo= r > example a nested class of a template class. > > Yes, it's a weak point but apparently some people have trouble with this. Not sure if it should be taken into account. > What I mean here is basically the same argument that makes Clang >> developers avoid anonymous namespaces. >> >> Also, I believe that the real thing I do want when I'm writing these >> generic libraries is actually to generate a whole bunch of types, using >> another type as argument of the process to generate the wanted types. >> > > We agree on that. > > >> Basically, I want one of the features that the Reflection group is >> supposed to look for. >> > > I'm working on statement-templates.googlecode.com but that's something I > will post in this list later. > > >> >> Since that realization, I think that efforts should be put to have a new >> reflection construct instead of making namespace do something too differ= ent >> from it's initial use. >> >> >> >> -- >> >> --- >> You received this message because you are subscribed to the Google Group= s >> "ISO C++ Standard - Future Proposals" group. >> To unsubscribe from this group and stop receiving emails from it, send a= n >> 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/. >> > > > > -- > Who=E2=80=99s got the sweetest disposition? > One guess, that=E2=80=99s who? > Who=E2=80=99d never, ever start an argument? > Who never shows a bit of temperament? > Who's never wrong but always right? > Who'd never dream of starting a fight? > Who get stuck with all the bad luck? > > -- > > --- > 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/. > --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --001a1139761cfe7aa7050629c0f2 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Sorry I didn't see your reply before.

On Sun, Jan 26, 2014 at 1:52 A= M, dgutson . <danielgutson@gmail.com> wrote:
On Wed, Jan 22, 2014 at 9:47 AM, Klaim= - Jo=C3=ABl Lamotte <mjklaim@gmail.com> wrote:
I had the exac= t same ideas few months ago after finding myself doing generic library whic= h all types would depend on the same type,
and remarking how much duplication could be avoi= ded if I was allowed to specify that a whole bunch of types would automatic= ally have an additional template parameter implicitly.

namespace b= lah< typename X >
{
=C2=A0 =C2=A0 =C2=A0class K {};
=C2=A0 =C2=A0 =C2=A0template < class T > class U {};
}

would be translated to=C2=A0

namespace blah
{
=C2=A0 =C2=A0 template< typename X >= ;
=C2=A0 =C2=A0 class K {};
=C2=A0 =C2=A0 template< typename X, class T > class = U {};
}


=
However, after weeks of thinking about thi= s I concluded that:

=C2=A01. namespace are not the appropriate construct for this, they really = are too different and not really encapsulating anything than names;
=C2=A02. there are a lot of potential issues relat= ed to the order of template arguments;

Please elaborate about the la= st two points.
=C2=A0

Basically, namespaces don't have a= unique definition and are only affecting naming.
Therefore, what= would be better to template would be something like a module or a class or= a mixin (a class component).

=C2=A0
=C2=A03. there is a potential issue for reading = the code as you need to see the namespace declaration before being able to = follow the rest of the code.

=
I don't find this issue different than any other template declarat= ion, for example a nested class of a template class.
=C2=A0

= Yes, it's a weak point but apparently some people have trouble with thi= s.
Not sure if it should be taken into account.
=C2=A0<= /div>
=C2=A0 =C2=A0 =C2=A0What I mean here is= basically the same argument that makes Clang developers avoid anonymous na= mespaces.

Also, I bel= ieve that the real thing I do want when I'm writing these generic libra= ries is actually to generate a whole bunch of types, using another type as = argument of the process to generate the wanted types.

We agree on that.
=C2=A0
Basically, I want one of the features that the R= eflection group is supposed to look for.



--
Who=E2=80=99s got the sweetest disposition?
One = guess, that=E2=80=99s who?
Who=E2=80=99d never, ever start an argument?<= br>Who never shows a bit of temperament?
Who's never wrong but alway= s right?
Who'd never dream of starting a fight?
Who get stuck with all the ba= d luck?=20

--
=C2=A0
---
You received this message because you are subscribed to the Google Groups &= quot;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.
Visit this group at http://groups.google.com/a/isocpp.org/gro= up/std-proposals/.

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
--001a1139761cfe7aa7050629c0f2-- .