220 26114 article Path: news.gmane.org!not-for-mail From: =?UTF-8?Q?Germ=C3=A1n_Diago?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: static_if, constraints, concepts, and definition checking Date: Wed, 1 Jun 2016 02:18:25 -0700 (PDT) Lines: 98 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_103_1393515859.1464772705211" X-Trace: ger.gmane.org 1464772724 7129 80.91.229.3 (1 Jun 2016 09:18:44 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 1 Jun 2016 09:18:44 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDC2VXM4YYDRBYWQXK5AKGQEAF5CAFQ@isocpp.org Wed Jun 01 11:18:39 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f200.google.com ([209.85.214.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1b82IP-0005Cc-Rv for gclcip-std-proposals@m.gmane.org; Wed, 01 Jun 2016 11:18:38 +0200 Original-Received: by mail-ob0-f200.google.com with SMTP id jt9sf8023746obc.2 for ; Wed, 01 Jun 2016 02:18:27 -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=rkpi1arbHkXGxCLOHHOj33adybGCCRxhbKReYItXTqo=; b=Q7oeIICytUGeC1t+vCUH05VRVH45DpXo/aZ1FcpQKVSTW+munp5F9jGNRAuBlmwvjM r2c+4CNg6gjQw+/rBOPASZDD0ZChqUgVuAz7j1MwhqZzfQCNr/TgUS4xGbAkzasCJAma q9w057H68xEDrocvsiW9KVPMUmXAg/Fdy/7k3QeTp9daZYTxaXyyIAIG3CH3mpQtbsRd s7pmPyFoTaQcyzz/4RyAbQVzOO7QDJvADLK5T6EYWyN3EG6uRLql7IEiF5+jbiPqkCNe rB0HY36r5f0W4BINStGCMRWcbsl0cex7Ajinet6KBEn3oz9WEqs7Q6CaaN1XADNdRbHY uPJQ== 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=rkpi1arbHkXGxCLOHHOj33adybGCCRxhbKReYItXTqo=; b=Ici2bztD8CrvjnC0Cg7zANfvPEiUti5EFEb3uz5zLbfcurPfyscIpA/QzLoSxx186s sIC1zRWBhH7MNn1nmeM92PwECgKUKDUK4Ae+9kxgyt6RhUOcZEwH9lqyGgRxUyXAqbG1 bsL2EhoQDlghMocus+0tY63Kz8DWKgPlL22jvwPjtI1ICMrXXVH2ePNoAeBetOfmp3GE 7UKpaQTgdvyJIJajXpE15e933yoo0K8g2eaylsTgeL0rpPFm8Lyk1rlMMmLErXPB4X65 PmOHsiuLqV5lSCiSXoHTDr0RGrCR//qDOwBlicKTIPqDtYRxLVmAcZEIvh4fZ9M5t8HJ SnnQ== 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=rkpi1arbHkXGxCLOHHOj33adybGCCRxhbKReYItXTqo=; b=k/hhu3ahCoToTvknkGkF+zWRWgpMlw/o27UeWcb9ZnwHMItoNtXW1vx7uVvMD2r+tU j6heHdha0Q3f7CV/tuc2p31VQ5uL5pTC4kgCq3zGV9bhQfXE4GZssUqXlBOO5wfWqitB 2a3HAgqvOhBNZrFfFd0jslpKovJD/ieo2zbvQA+3WAWRximO6dmEzgurWno0uuXZfLCb MBTDOzoYgnBm074IBP8JtnusXL29wYhYsLoI82ESejrObVKaGr//gobWsc31McsjPAin q/vcSwu3oLnz2La9QAgaddnULsgJgYNzCE1N6sy5iFHYqO3gmS4qkDpSozC2Z/mL2P5/ mubw== X-Gm-Message-State: ALyK8tLXRN2cFdMCv1NPLkUzs6YGgn7ip3a9WZKcGBxfzjS6XyHMLbxDloRTkBkB7VBXNw== X-Received: by 10.36.214.3 with SMTP id o3mr16109344itg.7.1464772706876; Wed, 01 Jun 2016 02:18:26 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.21.80 with SMTP id 74ls1964598qgk.3.gmail; Wed, 01 Jun 2016 02:18:25 -0700 (PDT) X-Received: by 10.140.28.182 with SMTP id 51mr1231963qgz.1.1464772705909; Wed, 01 Jun 2016 02:18:25 -0700 (PDT) In-Reply-To: X-Original-Sender: germandiago@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:26114 Archived-At: ------=_Part_103_1393515859.1464772705211 Content-Type: multipart/alternative; boundary="----=_Part_104_342734633.1464772705211" ------=_Part_104_342734633.1464772705211 Content-Type: text/plain; charset=UTF-8 > There is a semantic difference between *Constraints* and *Concepts*. > Actually I think that Constraints and Concepts are the same thing dressed differently. The fact that something becomes a concept or not is the author's choice. *| Concepts* are about something more than merely being `enable_if` without the crappy syntax. In which way is this different from a constraint? A Concept, in my view, is a constraint. | I think the Concepts TS can provide both constraints and concepts. I can see two ways of doing it: Why should we complicate things that far if they are essentially the same thing? I do not get your point about why they are different. Another question I have is: do concepts enable any use case not enabled by constraints (concepts-lite) in general? Because type-checking everything is going very far on complicating things, but, is this anything that has real use cases? I say this from complete ignorance: can concepts do anything (full concepts) that constraints (or concepts lite) cannot do besides full checking in a real-case scenario? Checking templates fully will also take compilation time, but not only that, it would complicate implementations. FWIW I am quite happy with the D approach + Concepts Lite. I am not sure full concepts should ever be needed, or even if it is worth to make a distinction, since I feel that distinction (correct me if I am wrong) is arbitrary. -- 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/a8dba456-b892-4778-9728-05311d5fc261%40isocpp.org. ------=_Part_104_342734633.1464772705211 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

There is a semantic difference between Constraints and C= oncepts.

Actually I think th= at Constraints and Concepts are the same thing dressed differently. The fac= t that something becomes a concept or not is the author's choice.
| Concepts are about something more than merely being `enable_if` = without the crappy syntax.

In which way is this different from a co= nstraint? A Concept, in my view, is a constraint.

| I think the Conc= epts TS can provide both constraints and concepts. I can see two ways of do= ing it:


Why should we complicate things that far if they are ess= entially the same thing? I do not get your point about why they are differe= nt.

Another question I have is: do concepts enable any use case not = enabled by constraints (concepts-lite) in general?
Because type-checkin= g everything is going very far on complicating things, but, is this anythin= g that has real use cases?
I say this from complete ignorance: can conc= epts do anything (full concepts) that constraints (or concepts lite) cannot= do
besides full checking in a real-case scenario? Checking templates fu= lly will also take compilation time, but not only that, it would complicate= implementations.
FWIW I am quite happy with the D approach + Concepts L= ite. I am not sure full concepts should ever be needed, or even if it is wo= rth to make a distinction,
since I feel that distinction (correct me if = I am wrong) is arbitrary.


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