220 28905 article Path: news.gmane.org!.POSTED!not-for-mail From: Giovanni Piero Deretta Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: generic dynamic / runtime cast (cast to real runtime type) Date: Sun, 16 Oct 2016 14:04:22 -0700 (PDT) Lines: 74 Approved: news@gmane.org Message-ID: References: <3d2ec365-84af-40e2-aa01-2807739716f8@isocpp.org> <4908423.ESY8U5GBX0@tjmaciei-mobl1> <39dc6003-567c-4506-9fbb-2e0340313960@isocpp.org> <09d1c64d-9207-4b2b-b134-45cb5cbbdf9e@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_1674_596928945.1476651862767" X-Trace: blaine.gmane.org 1476651881 30530 195.159.176.226 (16 Oct 2016 21:04:41 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 16 Oct 2016 21:04:41 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDEP3I7TGEINRVUPYACRUBDMRDS52@isocpp.org Sun Oct 16 23:04:37 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bvsbX-0005jN-Or for gclcip-std-proposals@m.gmane.org; Sun, 16 Oct 2016 23:04:23 +0200 Original-Received: by mail-pa0-f72.google.com with SMTP id hm5sf179275799pac.4 for ; Sun, 16 Oct 2016 14:04:26 -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=2Bks1t/EyELKjW/183NTkpxXd4YB3cH3XYK3n6ucn7k=; b=DynDPjmJN6LgMa/JNHyCCQjBreNahJiNq0Ciy1Ctaq3oElvDLTdiu8yQuQEH5QvtBP Ta6N56W2mhClac82SMJWmTjQnF0rI32gpwrnqh7zY0s/SmCbmQjtHp6LELomZ7MipsVS Gp6o5nAjRh9wqTLKyNaQwZaywoYFq+OeuCjEee4TC9u9vc5py1jWDUp4GIUrl1wVsv8z buW7uoUe1qRU5qSjtRzVC8GLdU5+2M+KEQwkCdiww51bKSbPVWo/eYB7PIhvvbPzrFe+ 3zAZsWOp8Eguc+Su3VNyOLSlJ+dL8OGXCNTNbW2Xy02GE4uca41+itdXWnxd5joLFHEV zAzw== 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=2Bks1t/EyELKjW/183NTkpxXd4YB3cH3XYK3n6ucn7k=; b=eT7AIWZnbBK5NpyG9QnJy+/sfxDUH1LERcUvr3ttl4caEIp6haKZ4lV85R9JHQFAtA 5tPkWfQHnpnSZt+3PqPg5QsmUNtA8j6Be5z2p6W2wfFIb0abI7uhrYh/Lzsv5IFN7nQ0 knyOx117sWo8Oh6MRnFGRWlGc6G3FupeyL7GVnbF2uQOdcjwM3iLkKjVdjgsxNnQamC+ frSVsmkloUQPnbBVj53oQkTu1qPE7fV0zJQqO6VrlgNAw4TOWzEzEh89Q0gDkCScJT3I nq2awwDXEx45rirTfFGA4LnIw7qSWd92Sa3mmdHxvMiHCXiaQwwEtXIKMVhnkfAg6IPL JcEA== 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=2Bks1t/EyELKjW/183NTkpxXd4YB3cH3XYK3n6ucn7k=; b=Kf+KYT5lCvWODcWXvZdaJGC3OeTwnWmJs2GRJmn4zfVnato1jX0hLzwdXL4mCb+fbq e0Ues5NDELkPustsPDDzzmA5byuh9JNIA0Y7rwZBdczd9r1dT5V4viCZutea4FmOokdH dqMEmgZAv6NjNOG0/QNA0CyY+3waCge6lHGGVku13hSv/TyJP3HyPLUieKe8ZrxBgNeT hwrQZxG0IrljEnt4YimguDHslTQIVK6tzJ/FLVKIvIoJ0mDXrV3etIMVI6eDoZN3fDFz IET1JrOWevxOleP2qhOktDA6k8nxmToYB59jT8EbfASzQWR9Qnx0c4XUVY07eUTmqy23 aYyQ== X-Gm-Message-State: AA6/9RmTq56qLIYTz6dtDuNrBoPWO6MmW0SSb1eeFxE9rsJxFoPG3pQrKXZHyKlH4bqMdQ== X-Received: by 10.66.124.195 with SMTP id mk3mr5106018pab.42.1476651865519; Sun, 16 Oct 2016 14:04:25 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.19.200 with SMTP id 69ls3955649iot.4.gmail; Sun, 16 Oct 2016 14:04:23 -0700 (PDT) X-Received: by 10.36.77.75 with SMTP id l72mr245899itb.1.1476651863851; Sun, 16 Oct 2016 14:04:23 -0700 (PDT) In-Reply-To: <09d1c64d-9207-4b2b-b134-45cb5cbbdf9e@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:28905 Archived-At: ------=_Part_1674_596928945.1476651862767 Content-Type: multipart/alternative; boundary="----=_Part_1675_843545225.1476651862767" ------=_Part_1675_843545225.1476651862767 Content-Type: text/plain; charset=UTF-8 On Sunday, October 16, 2016 at 7:03:14 PM UTC+1, Nicol Bolas wrote: [...] > C++ is a statically typed language. What you're talking about requires > dynamic dispatching of a kind that C++ as a language is simply not capable > of. Not without adding a bunch of hacks to the language. > > C++ has dynamic dispatching, but it is restricted only on the first parameter of virtual function calls. There was a paper sometimes ago Stroustrup about a possible efficient implementation of multiple dispatch for C++ [1], but there isn't really enough support to get it into the language. C# dynamic is a great feature, but to perform decently needs a powerful runtime/JIT. I do not think it would work well in C++. Multimethods would be nice though. [1] Open Multimethods in C++. -- gpd -- 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/de8050cf-117b-46e6-b2de-329db8d2bfca%40isocpp.org. ------=_Part_1675_843545225.1476651862767 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Sunday, October 16, 2016 at 7:03:14 PM UTC+1, Nicol Bol= as wrote:
[...]
=
C++ is a statically typed language. What you're talkin= g about requires dynamic dispatching of a kind that C++ as a language is si= mply not capable of. Not without adding a bunch of hacks to the language.


C++ has dynamic dispatching, b= ut it is restricted only on the first parameter of virtual function calls. = There was a paper sometimes ago Stroustrup about a possible efficient imple= mentation of multiple dispatch for C++ [1], but there isn't really enou= gh support to get it into the language.

C# dynamic is a great featu= re, but to perform decently needs a powerful runtime/JIT. I do not think it= would work well in C++. Multimethods would be nice though.

[1]=C2= =A0 Open Multimethods in C++.

-- gpd

--
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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.
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