220 8809 article Path: news.gmane.org!not-for-mail From: "dgutson ." Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Templetized namespaces Date: Sat, 25 Jan 2014 22:22:38 -0200 Lines: 276 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=bcaec52beba5b2dc0304f0d49670 X-Trace: ger.gmane.org 1390695756 1673 80.91.229.3 (26 Jan 2014 00:22:36 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 26 Jan 2014 00:22:36 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDE3NBMV6UFBBUNKSGLQKGQE3DKKW3I@isocpp.org Sun Jan 26 01:22:44 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lb0-f199.google.com ([209.85.217.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1W7DUo-0001ke-2D for gclcip-std-proposals@m.gmane.org; Sun, 26 Jan 2014 01:22:42 +0100 Original-Received: by mail-lb0-f199.google.com with SMTP id l4sf8931081lbv.6 for ; Sat, 25 Jan 2014 16:22:41 -0800 (PST) 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=NbbOKGE0XHE8LUDMKv2i2fhnD1YvAgDApAdiivO/bPM=; b=YnWwfVQ4VX4dYHOuJjfGg/SQY8d10z3kmVeJYto3KwgSjZq/9bsx4V2oZ/avk8sCO6 4Lb1DDlILCJWGlJmGhXzM0tWkUa2zbLMjw3RTMyA+Frlwg63tvntnkM8zmP9mQuEIALK PGjVZPCz0A1XG0h4axslpa81KWMo1+h99m74u8L+8N/w4ZVEIg0xCOBvEV7QqMNIl68I D3KOst9RZN4n0+8Qx3Mjmvi/5Er/aQFWjTOEj7VQEIt9DDk2Xagqh0XTotWC0mPTBZcO SrSupFsR7p2h0LYe6swQEnEla/8JoM3fyyUb37B0P64KgH+cE1+VFoEuOSwyz9kfGH7F mY3Q== X-Gm-Message-State: ALoCoQnwrWPHykftj6Y8pfT52Wur88hpjZT74yKTDQnB7/SpmTIt1Fixr0JZ4WVM7LhsnjG1PPxj X-Received: by 10.112.223.8 with SMTP id qq8mr4558430lbc.9.1390695761559; Sat, 25 Jan 2014 16:22:41 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.90.178 with SMTP id bx18ls682789wib.26.canary; Sat, 25 Jan 2014 16:22:40 -0800 (PST) X-Received: by 10.204.117.139 with SMTP id r11mr14015236bkq.37.1390695760765; Sat, 25 Jan 2014 16:22:40 -0800 (PST) Original-Received: from mail-pd0-x231.google.com (mail-pd0-x231.google.com [2607:f8b0:400e:c02::231]) by mx.google.com with ESMTPS id h4si8486633bkr.258.2014.01.25.16.22.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 25 Jan 2014 16:22:40 -0800 (PST) Received-SPF: pass (google.com: domain of danielgutson@gmail.com designates 2607:f8b0:400e:c02::231 as permitted sender) client-ip=2607:f8b0:400e:c02::231; Original-Received: by mail-pd0-f177.google.com with SMTP id x10so4431838pdj.36 for ; Sat, 25 Jan 2014 16:22:38 -0800 (PST) X-Received: by 10.66.27.107 with SMTP id s11mr22464505pag.64.1390695758878; Sat, 25 Jan 2014 16:22:38 -0800 (PST) Original-Received: by 10.70.78.200 with HTTP; Sat, 25 Jan 2014 16:22:38 -0800 (PST) In-Reply-To: <4cfc2db6-97da-4750-9296-5aaaa3475014@isocpp.org> X-Original-Sender: danielgutson@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of danielgutson@gmail.com designates 2607:f8b0:400e:c02::231 as permitted sender) smtp.mail=danielgutson@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:8809 Archived-At: --bcaec52beba5b2dc0304f0d49670 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sun, Jan 19, 2014 at 3:16 PM, Andrew Tomazos wr= ote: > Namespaces differ from classes in that they can be split within and > amongst translation units. The definition of a namespace is not required > to be the same in different translation units. Multiple namespace > definitions of the same namespace in the same translation unit are > logically merged into one (the first is called the original, the followin= g > are called extensions). > > How do template namespace specialization and template namespace > instantiation interact with these new properties that are not present in > other template entities? > > Also namespaces can contain the following declarations, whereas classes > cannot: > > explicit-instantiation > explicit-specialization > linkage-speci=EF=AC=81cation > namespace-de=EF=AC=81nition > attribute-declaration > asm-de=EF=AC=81nition > namespace-alias-de=EF=AC=81nition > using-directive > opaque-enum-declaration > > Now that all these are possible member declarations of a template entity, > how are they handled? > > Also you need to think about program initialization. The members of a > namespace have a bunch of rules about when they are initialized and in wh= at > order. How will these rules interact with template namespace instances? > I understand that, in terms of a standard, all these considerations have to be taken into account. That's why I call for help here. Please note that the very concrete problem I'm referring to still holds and IMHO is relevant. I kindly invite you that, if you agree, begin drawing with me the possible rules for addressing all the points that you mentioned. > > The best approach for this type of feature would be to put together an > experimental compiler extension to gcc or clang that implements template > namespaces. This would shake out all the above issues (and likely more) > which you could then use as the basis of a proposal. > Despite I was a gcc maintainer in the past, I don't have the resources for a full fledged implementation of this (specially since I mostly maintained the ARM backend). Nevertheless, I'll see what I can do with a plugin to get a proof-of-concept by using a template class to mimick the semantic of a template namespace. My initial idea is that the original template will be translated by the plugin as a base class, and the extensions as derived classes in a fixed order of inheritance. But please, still consider my call for help while I manage to try a plugin like this. Thanks, Daniel. > > On Sunday, January 19, 2014 6:26:57 PM UTC+1, dgutson . wrote: >> >> Hi. >> >> I found a number of situations where the ability to templetize >> namespaces would be very useful. >> >> My latest use case is this: I'm writing a library that is configured >> through a number of (non-type) template arguments. Such configuration >> affects to all the classes of the library. To be more specific, it's a >> fault-tolerant library for the aerospace industry where the whole librar= y >> is tuned with some integers (some of then related to redundancy due to >> ionizing radiation). >> >> The most natural thing would be to put all the classes in a namespace, >> and let the namespace be templetized with such arguments. >> Moreover, a using namespace with the appropriate arguments would suffice >> for all the application. For example: >> >> using namespace TheLibrary; >> >> I didn't write the proposal yet, since I'd like to get some feedback. >> >> Thanks, >> >> Daniel. >> >> ps: The library will be available soon and uses template metaprogramming >> based on the arguments. >> >> >> -- >> 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 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? --=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/. --bcaec52beba5b2dc0304f0d49670 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable



On Sun, Jan 19, 2014 at 3:16 PM, Andrew Tomazos &= lt;andrewtomaz= os@gmail.com> wrote:
Namespaces differ from clas= ses in that they can be split within and amongst translation units. =C2=A0T= he definition of a namespace is not required to be the same in different tr= anslation units. =C2=A0Multiple namespace definitions of the same namespace= in the same translation unit are logically merged into one (the first is c= alled the original, the following are called extensions).

How do template namespace specialization and template namesp= ace instantiation interact with these new properties that are not present i= n other template entities?

Also namespaces can con= tain the following declarations, whereas classes cannot:

explicit-instantiation
explicit-spec= ialization
linkage-speci=EF=AC=81cation
namespace-de=EF= =AC=81nition
attribute-declaration
asm-de=EF=AC=81n= ition
namespace-alias-de=EF=AC=81nition
using-directive
o= paque-enum-declaration

Now that all thes= e are possible member declarations of a template entity, how are they handl= ed?

Also you need to think about program initialization. = =C2=A0The members of a namespace have a bunch of rules about when they are = initialized and in what order. =C2=A0How will these rules interact with tem= plate namespace instances?

I understand that, in terms of a sta= ndard, all these considerations have to be taken into account. That's w= hy I call for help here. Please note that the very concrete problem I'm= referring to still holds and IMHO is relevant. I kindly invite you that, i= f you agree, begin drawing with me the possible rules for addressing all th= e points that you mentioned.
=C2=A0

<= /div>
The best approach for this type of feature would be to put togeth= er an experimental compiler extension to gcc or clang that implements templ= ate namespaces. =C2=A0This would shake out all the above issues (and likely= more) which you could then use as the basis of a proposal.

Despite I was a gcc maintainer in th= e past, I don't have the resources for a full fledged implementation of= this (specially since I mostly maintained the ARM backend). Nevertheless, = I'll see what I can do with a plugin to get a proof-of-concept by using= a template class to mimick the semantic of a template namespace. My initia= l idea is that the original template will be translated by the plugin as a = base class, and the extensions as derived classes in a fixed order of inher= itance.
But please, still consider my call for help while I manage to try a pl= ugin like this.

Thanks,

= =C2=A0 =C2=A0Daniel.
=C2=A0

On Sunday, Janu= ary 19, 2014 6:26:57 PM UTC+1, dgutson . wrote:
Hi.

=C2=A0 =C2=A0I found a number of si= tuations where the ability to templetize namespaces would be very useful.

My latest use case is this: I'm writing a libra= ry that is configured through a number of (non-type) template arguments. Su= ch configuration affects to all the classes of the library. To be more spec= ific, it's a fault-tolerant library for the aerospace industry where th= e whole library is tuned with some integers (some of then related to redund= ancy due to ionizing radiation).

The most natural thing would be to put all the classes = in a namespace, and let the namespace be templetized with such arguments.
Moreover, a using namespace with the appropriate arguments would s= uffice for all the application. For example:

=C2=A0 =C2=A0 using namespace TheLibrary<arg1, arg2,= arg3>;

I didn't write the proposal yet, si= nce I'd like to get some feedback.

Thanks,

=C2=A0 =C2=A0Daniel.

ps: The librar= y will be available soon and uses template metaprogramming based on the arg= uments.


--
Who=E2=80=99s got= the sweetest disposition?
One guess, that=E2=80=99s who?
Who=E2=80=99d never, ever start an argume= nt?
Who never shows a bit of temperament?
Who's never wrong but a= lways right?
Who'd never dream of starting a fight?
Who get stuck= with all the bad 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/.



-- 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 b= it of temperament?
Who's never wrong but always right?
Who'd never dream of startin= g a fight?
Who get stuck with all the bad luck?=20

--
 
---
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/group/std-proposals/<= /a>.
--bcaec52beba5b2dc0304f0d49670-- .