220 5994 article Path: news.gmane.org!not-for-mail From: stackmachine@hotmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Proposal: Mixins for C++ Date: Thu, 29 Aug 2013 17:59:59 -0700 (PDT) Lines: 117 Approved: news@gmane.org Message-ID: References: <787081f7-fb40-4507-907d-259318ef2000@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_159_29370498.1377824399570" X-Trace: ger.gmane.org 1377824404 5478 80.91.229.3 (30 Aug 2013 01:00:04 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 30 Aug 2013 01:00:04 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDC7BQ4GSIMRBEG576IAKGQE7L5ZV6Q@isocpp.org Fri Aug 30 03:00:02 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-gh0-f199.google.com ([209.85.160.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VFD4E-0004Ge-15 for gclcip-std-proposals@m.gmane.org; Fri, 30 Aug 2013 03:00:02 +0200 Original-Received: by mail-gh0-f199.google.com with SMTP id g14sf1253786ghb.6 for ; Thu, 29 Aug 2013 18:00:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; 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=e5gI3/t9HHgFckoBit4lEb86EzvXvvbE/9j2Iq8RUuw=; b=Z6fjklV7Xr2gHyB8NjGYfA+CwxP3pHkOJ88lHII+3muH6sx0Zw4wEN353w+9WgUylf 6xMavblkjvNgGkBFBgl9QRSle2KTuTu5K+CizN91K3E8cnLCP4jpBPBZlzJOCbwNM0mT +KrGpc1Bi26ECmBK4jI/ufMfZ+askuJXOYQUsIIiTBhy9If6oF5GmGpPTm2ytD4KVYI+ AF8tIrm5yr6BJSpU6bX3Kg0/aHBMIWTLU32/qs03bpt0M7CKW090MiQAw/hM3Y8jwCtR yXUKaAUDYfYRi0QNawcBpXF2tPsMmut82uaca/B0N2qRBp2tPwfU1OK/2L5rW1xHSONp /Zcw== X-Received: by 10.236.109.134 with SMTP id s6mr2182007yhg.32.1377824401085; Thu, 29 Aug 2013 18:00:01 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.70.228 with SMTP id p4ls1134742qeu.43.gmail; Thu, 29 Aug 2013 18:00:00 -0700 (PDT) X-Received: by 10.49.12.162 with SMTP id z2mr2333qeb.14.1377824400163; Thu, 29 Aug 2013 18:00:00 -0700 (PDT) In-Reply-To: <787081f7-fb40-4507-907d-259318ef2000@isocpp.org> X-Original-Sender: stackmachine@hotmail.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:5994 Archived-At: ------=_Part_159_29370498.1377824399570 Content-Type: text/plain; charset=ISO-8859-1 I very much like this idea. Two things: - There has been at least a thread to propose decltype(class) to mean "the type of the current class". This is what __THIS_CLASS__ is supposed to be, with a nice syntax imo. - I've had an idea in my head for a long time that seems to be much more flexible than yours. I call it "code generators". The best way to explain this feature is probably using an example. codegen noncopyable() { emit { decltype(class)(decltype(class) const&) = delete; decltype(class)& operator = (decltype(class) const&) = delete; } } This thing is not just a macro with better syntax, it is a fully-fledged constexpr function that can have compiletime-loops and use compiletime reflection to generate code. The only difference to a regular constexpr function is that it does not have a return type and instead emits code. Let's see how this can be used: struct Foo { $noncopyable() // special call syntax could be using the $-sign or some other currently unused character }; Another idea I had is a special "operator emit" that can be overloaded by classes to allow us to carry code around statefully. I have not yet put enough thought into this though. -- --- 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/. ------=_Part_159_29370498.1377824399570 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I very much like this idea. Two things:
  • There h= as been at least a thread to propose decltype(class) to mean "the type of t= he current class". This is what __THIS_CLASS__ is supposed to be, with a ni= ce syntax imo.
  • I've had an idea in my head for a long time that see= ms to be much more flexible than yours. I call it "code generators".
    Th= e best way to explain this feature is probably using an example.
<= p>

=
codegen noncopyable()
{
    emit
    {
    <= code class=3D"prettyprint">    decltype(class)(decltype(class) const&) =3D del= ete;
    =     decltype(class)& operator =3D (de= cltype(class) const&) =3D delete;
    }
}
This thing is not just a macro with better syntax, it is a f= ully-fledged constexpr function that can have compiletime-loops and use com= piletime reflection to generate code. The only difference to a regular cons= texpr function is that it does not have a return type and instead emits cod= e.

Let's see how this can be used:

struct Foo
{
    $noncopyable() // special call syntax could be using the $-sign or= some other currently unused character
};
Another idea I had is a special "operator emit" that can be overloaded by classes to allow us to carry code around= statefully. I have not yet put enough thought into this though.
=

--
 
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