220 41206 <9fa1b055-91e4-3a90-3aba-340efa5db725@wanadoo.fr> article Path: news.gmane.org!.POSTED!not-for-mail From: "Vicente J. Botet Escriba" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Proposal: Extensions of Scoped Enumerations Date: Mon, 3 Dec 2018 07:57:31 +0100 Lines: 138 Approved: news@gmane.org Message-ID: <9fa1b055-91e4-3a90-3aba-340efa5db725@wanadoo.fr> References: <506ba0a8-2d6b-4a4d-8fe8-b5e94d232365@isocpp.org> <82c331a0-fb81-4b67-8a7e-c5a6b8929e00@isocpp.org> <43b3f4ec-fd19-4144-bf24-067ce587e071@isocpp.org> <9e3bba78-04c2-42d5-b522-2712932c1659@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------------913A562C87EF390F90EE6AE6" X-Trace: blaine.gmane.org 1543820129 12215 195.159.176.226 (3 Dec 2018 06:55:29 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 3 Dec 2018 06:55:29 +0000 (UTC) User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:60.0) Gecko/20100101 Thunderbird/60.3.2 To: std-proposals@isocpp.org, philipgins@gmail.com Original-X-From: std-proposals+bncBDH67CONY4PBBXVHSPQAKGQE3IMRMYA@isocpp.org Mon Dec 03 07:55:25 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wr1-f71.google.com ([209.85.221.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gTi8b-00034Q-4b for gclcip-std-proposals@m.gmane.org; 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[80.12.242.123]) by mx.google.com with ESMTPS id m12si4875034wmc.50.2018.12.02.22.57.34 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 02 Dec 2018 22:57:34 -0800 (PST) Received-SPF: neutral (google.com: 80.12.242.123 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) client-ip=80.12.242.123; Original-Received: from imac-de-vicente-botet-escriba.home ([83.205.44.191]) by mwinf5d48 with ME id 7JxY1z00B47V06j03JxZ9o; Mon, 03 Dec 2018 07:57:34 +0100 X-ME-Helo: imac-de-vicente-botet-escriba.home X-ME-Auth: dmljZW50ZS5ib3RldEB3YW5hZG9vLmZy X-ME-Date: Mon, 03 Dec 2018 07:57:34 +0100 X-ME-IP: 83.205.44.191 In-Reply-To: Content-Language: en-US X-Original-Sender: vicente.botet@wanadoo.fr X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 80.12.242.123 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) smtp.mailfrom=vicente.botet@wanadoo.fr 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:41206 Archived-At: This is a multi-part message in MIME format. --------------913A562C87EF390F90EE6AE6 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: quoted-printable Le 02/12/2018 =C3=A0 22:22, philipgins@gmail.com a =C3=A9crit=C2=A0: > @Vicente: > I have reworked the introduction=20 > =20 > and inserted a discussion chapter using the week day example that you=20 > provided, thank you very much for it. Do you think this is clearer now? > Yes, it is better. I'll see if I can propose some improvements. The use of extension could be misleading as other languages uses extends=20 for inheritance. The systax part could talk about the possible use of <: as a sub-tyte=20 relationship between enums, even if you are not proposing it. BTW, concerning restriction, the fact that we can express it as a=20 predicate, is not a good rationale to don't have a mechanism to define a=20 type. See how we are introducing types as not_null in the GSL. More I think on your example and more I believe there is something wrong=20 with it as motivating example. While I agree with you that a Tokenizer=20 has not to use a SyntaxType enum, I don't see why a Parser must mix=20 TokenTypes and SyntaxTypes. A Syntax Node is not a Token Node. We have=20 the token ':' but we don't have an associated syntax type. Having to do=20 the explicit mapping from TokenType to SyntaxType seems to me the best.=20 I don't believe this would pass code review with our standards. What is=20 the cost of not having using this feature on this example? As I say,=20 this implies to do some kind of conversion at some time. This=20 conversions is defined by the user and so must be maintained. It could=20 have a little run-time penalty. BTW, what happens with your example if=20 we add new TokenTypes. I believe we need a better example for=20 extensions. I'll think a little bit on that. Hopping this helps, Vicente --=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/9fa1b055-91e4-3a90-3aba-340efa5db725%40wanadoo.f= r. --------------913A562C87EF390F90EE6AE6 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Le 02/12/2018 =C3=A0 22:22, philipgins@gmail.com a =C3=A9crit=C2=A0:
@Vicente:
I have reworked the introduction and inserted a discussion chapter using the week day example that you provided, thank you very much for it. Do you think this is clearer now?

Yes, it is better. I'll see if I can propose some improvements.

The use of extension could be misleading as other languages uses extends for inheritance.

The systax part could talk about the possible use of <: as a sub-tyte relationship between enums, even if you are not proposing it.

BTW, concerning restriction, the fact that we can express it as a predicate, is not a good rationale to don't have a mechanism to define a type. See how we are introducing types as not_null<Ptr> in the GSL.

More I think on your example and more I believe there is something wrong with it as motivating example. While I agree with you that a Tokenizer has not to use a SyntaxType enum, I don't see why a Parser must mix TokenTypes and SyntaxTypes. A Syntax Node is not a Token Node. We have the token ':' but we don't have an associated syntax type. Having to do the explicit mapping from TokenType to SyntaxType seems to me the best. I don't believe this would pass code review with our standards. What is the cost of not having using this feature on this example? As I say, this implies to do some kind of conversion at some time. This conversions is defined by the user and so must be maintained. It could have a little run-time penalty. BTW, what happens with your example if we add new TokenTypes. I believe we need a better example for extensions. I'll think a little bit on that.


Hopping this helps,

Vicente

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