220 28084 article Path: news.gmane.org!.POSTED!not-for-mail From: "'Edward Catmur' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Make (strongly typed) enums castable to char const * const Date: Wed, 31 Aug 2016 22:11:13 +0100 Lines: 140 Approved: news@gmane.org Message-ID: References: <878tvfl89r.fsf@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=94eb2c0560d68fce98053b6489ef X-Trace: blaine.gmane.org 1472677881 22505 195.159.176.226 (31 Aug 2016 21:11:21 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 31 Aug 2016 21:11:21 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDZLZTXF7UJBB4UPTW7AKGQEGIHVP4I@isocpp.org Wed Aug 31 23:11:17 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-it0-f70.google.com ([209.85.214.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bfCmx-0005Ci-4x for gclcip-std-proposals@m.gmane.org; Wed, 31 Aug 2016 23:11:15 +0200 Original-Received: by mail-it0-f70.google.com with SMTP id g185sf102136093ith.2 for ; Wed, 31 Aug 2016 14:11:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=2uohrRc2tMOljwW37xo8m6STZCExbI9BYgv3hxaT2mI=; b=XkC7TmxeLbf64D27AHBW0UHB9vwqf9H9+Ve6MRbHmWpU/9pDUZX/XtKOLHhw0yuivR y+ylj/G7OGHQGmBtFlctNgQ2juUnDn1/qtybErZCBf5FerBPz0rEWCkVC31zU4KdRwBP ZA8SHTCimCrxA48QwrADtCHJVoptbRjBRa1SProLN08YIFfq8POjURyTCsABQ+41Wln8 D2EC2l3zQQgoceVR9Fcmt5/pv6mEelaaaAtzwLfB9TvxIBUvI16YBLO1syybx9riFMik HHJ7lIYoxFcYZ3E+MK6cyLeFt0DrW3RM2gAYbyDuEx7nOjPof0TXS/85FgZxrwy4pbUL s2HQ== 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:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=2uohrRc2tMOljwW37xo8m6STZCExbI9BYgv3hxaT2mI=; b=FnOrlzzPn4h1Em9KAqfu/EC/R3PzdnJfpbYWYE1rTNycQ87ZHkzAWZR68GxUScm/8W CpftnhRJCotsJ7zAj1Nwl+wVJWq3m7lkO3P6DNTV5B89or2cK+jc9/NjnJxMvc+FLL1p 0X3HFfUwSl5Uun7AQTLO/o1Chofn5+8JJfd9N/tpNpSxP8hZBT6Hb43VfEOjuCgILRmp E03LUhkAQfwqvbStuXavfB0ORzLTT9jCQqeKHQUxU8eAXBKYsPpJNWpjZJ236ECObeCu YuhB+ei4fVvtH823Cx2kE5tyWOVoqU1FtdFLIXgrs60goSCNCVQjtNOEkOsCnx0HbOfR KTTg== X-Gm-Message-State: AE9vXwMc51L1QCMQOLI5K5YowhHiH9jvjyMK8OPdPxZA+8oaHHccaukNMrawhIy4U3LfDA== X-Received: by 10.237.49.36 with SMTP id 33mr8976911qtg.15.1472677875830; Wed, 31 Aug 2016 14:11:15 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.52.249 with SMTP id t54ls5028934otd.2.gmail; Wed, 31 Aug 2016 14:11:14 -0700 (PDT) X-Received: by 10.55.192.135 with SMTP id v7mr12919838qkv.236.1472677874660; Wed, 31 Aug 2016 14:11:14 -0700 (PDT) Original-Received: from mail-qk0-x22f.google.com (mail-qk0-x22f.google.com. [2607:f8b0:400d:c09::22f]) by mx.google.com with ESMTPS id f189si1338703qkb.297.2016.08.31.14.11.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Aug 2016 14:11:14 -0700 (PDT) Received-SPF: pass (google.com: domain of ecatmur@googlemail.com designates 2607:f8b0:400d:c09::22f as permitted sender) client-ip=2607:f8b0:400d:c09::22f; Original-Received: by mail-qk0-x22f.google.com with SMTP id z190so65370917qkc.0 for ; Wed, 31 Aug 2016 14:11:14 -0700 (PDT) X-Received: by 10.55.140.131 with SMTP id o125mr13537343qkd.17.1472677874209; Wed, 31 Aug 2016 14:11:14 -0700 (PDT) Original-Received: by 10.237.32.135 with HTTP; Wed, 31 Aug 2016 14:11:13 -0700 (PDT) In-Reply-To: X-Original-Sender: ecatmur@googlemail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@googlemail.com; spf=pass (google.com: domain of ecatmur@googlemail.com designates 2607:f8b0:400d:c09::22f as permitted sender) smtp.mailfrom=ecatmur@googlemail.com; dmarc=pass (p=QUARANTINE dis=NONE) header.from=googlemail.com X-Original-From: Edward Catmur 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:28084 Archived-At: --94eb2c0560d68fce98053b6489ef Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wed, Aug 31, 2016 at 9:20 PM, Vicente J. Botet Escriba < vicente.botet@wanadoo.fr> wrote: > Le 30/08/2016 =C3=A0 13:05, Edward Catmur a =C3=A9crit : > > On Tuesday, 30 August 2016 06:23:04 UTC+1, Matus Chochlik wrote: >> >> I've added few examples showing simple implementation of >> enumerator-to-string and string-to-enumerator using both the TMP and >> constexpr MP libraries to the mirror reflection utilities: >> >> https://github.com/matus-chochlik/mirror/blob/develop/exampl >> e/mirror/005_enum_to_string.cpp >> https://github.com/matus-chochlik/mirror/blob/develop/exampl >> e/mirror/006_string_to_enum.cpp >> https://github.com/matus-chochlik/mirror/blob/develop/exampl >> e/puddle/005_enum_to_string.cpp >> https://github.com/matus-chochlik/mirror/blob/develop/exampl >> e/puddle/006_string_to_enum.cpp >> > > Is it really necessary to construct the lookup table as a library > container? Wouldn't a switch statement perform better? > > No, we don't need a map, but I believe that Matus wanted to show a probe > of concept. > > I don't know how we can generate a switch with the current language. We > can do some recursive if and expect that the compiler optimize it. > Fair enough; recursive templates are even worse, so a container is the simplest option for now. You can generate a switch with the preprocessor, but then you have to set an (arbitrary) upper limit on the number of cases. We really need variadic expansion of case labels, but I guess it's a fairly niche interest. --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/CAJnLdOZAFnHVov-%2BRWp2JwjFjLp5ZpnRW7PmLgAiFCv%3= Dx_4a_w%40mail.gmail.com. --94eb2c0560d68fce98053b6489ef Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Wed, Aug 31, 2016 at 9:20 PM, Vicente J. Botet Escriba <vice= nte.botet@wanadoo.fr> wrote:
Le 30/08/2016 =C3=A0 13:05, Edward Catmur a =C3=A9crit=C2=A0:
On Tuesday, 30 August 2016 06:23:04 UTC+1, Matus Chochlik wrote:
I've added few examples showing simple implementation of
enumerator-to-string and string-to-enumerator using both the TMP and
constexpr MP libraries to the mirror reflection utilities:

h= ttps://github.com/matus-chochlik/mirror/blob/develop/example/mirr= or/005_enum_to_string.cpp
h= ttps://github.com/matus-chochlik/mirror/blob/develop/example/mirr= or/006_string_to_enum.cpp
h= ttps://github.com/matus-chochlik/mirror/blob/develop/example/pudd= le/005_enum_to_string.cpp
h= ttps://github.com/matus-chochlik/mirror/blob/develop/example/pudd= le/006_string_to_enum.cpp=C2=A0
=C2=A0
Is it really necessary to construct the lookup table as a library container? Wouldn't a switch statement perform better= ?

 No, we don't need a map, but I believe that Matus wanted to show a probe of concept.

I don't know how we can generate a switch with the current language= .. We can do some recursive if and expect that the compiler optimize it.

Fair enough; recursive templa= tes are even worse, so a container is the simplest option for now. You can = generate a switch with the preprocessor, but then you have to set an (arbit= rary) upper limit on the number of cases. We really need variadic expansion= of case labels, but I guess it's a fairly niche interest.
<= br>

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