From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#40671: [DOC] modify literal objects Date: Fri, 24 Apr 2020 19:21:17 -0700 Organization: UCLA Computer Science Department Message-ID: <969b3497-0afd-d104-6792-d744d31548fa@cs.ucla.edu> References: <83tv1finob.fsf@gnu.org> <1E9E4C19-37C2-4E24-91B7-8101F9CFBF35@acm.org> <527dc4b5-3176-38b5-f2c1-1483ffc814a1@cs.ucla.edu> <87k12b6sv2.fsf@web.de> <2225099d-16e1-645d-0342-a054da53363f@cs.ucla.edu> <87a7376nv9.fsf@web.de> <99d7a8f9-7732-e1e3-414e-aabbea4433ac@cs.ucla.edu> <87o8rnasfk.fsf@web.de> <9e6c138d-cb9f-6075-34df-a8d1d931343b@cs.ucla.edu> <871rofxbz9.fsf@web.de> <93463227-33a8-85a0-fd19-8b29b75997f3@yandex.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="86764"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Cc: Michael Heerdegen , ke.vigouroux@laposte.net, 40671@debbugs.gnu.org To: Dmitry Gutov , Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= , Richard Stallman Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Apr 25 04:22:14 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jSASL-000MTy-Mg for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 25 Apr 2020 04:22:13 +0200 Original-Received: from localhost ([::1]:56664 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jSASK-00067b-9V for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 24 Apr 2020 22:22:12 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:57450) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jSASB-00067F-7J for bug-gnu-emacs@gnu.org; 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Fri, 24 Apr 2020 19:21:17 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 5lcDSNEo_4IK; Fri, 24 Apr 2020 19:21:17 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 720B816008D; Fri, 24 Apr 2020 19:21:17 -0700 (PDT) Autocrypt: addr=eggert@cs.ucla.edu; prefer-encrypt=mutual; keydata= LS0tLS1CRUdJTiBQR1AgUFVCTElDIEtFWSBCTE9DSy0tLS0tCgptUUlOQkV5QWNtUUJFQURB QXlIMnhvVHU3cHBHNUQzYThGTVpFb243NGRDdmM0K3ExWEEySjJ0QnkycHdhVHFmCmhweHhk R0E5Smo1MFVKM1BENGJTVUVnTjh0TFowc2FuNDdsNVhUQUZMaTI0NTZjaVNsNW04c0thSGxH ZHQ5WG0KQUF0bVhxZVpWSVlYL1VGUzk2ZkR6ZjR4aEVtbS95N0xiWUVQUWRVZHh1NDd4QTVL aFRZcDVibHRGM1dZRHoxWQpnZDdneDA3QXV3cDdpdzdlTnZub0RUQWxLQWw4S1lEWnpiRE5D UUdFYnBZM2VmWkl2UGRlSStGV1FONFcra2doCnkrUDZhdTZQcklJaFlyYWV1YTdYRGRiMkxT MWVuM1NzbUUzUWpxZlJxSS9BMnVlOEpNd3N2WGUvV0szOEV6czYKeDc0aVRhcUkzQUZINmls QWhEcXBNbmQvbXNTRVNORnQ3NkRpTzFaS1FNcjlhbVZQa25qZlBtSklTcWRoZ0IxRApsRWR3 MzRzUk9mNlY4bVp3MHhmcVQ2UEtFNDZMY0ZlZnpzMGtiZzRHT1JmOHZqRzJTZjF0azVlVThN Qml5Ti9iClowM2JLTmpOWU1wT0REUVF3dVA4NGtZTGtYMndCeHhNQWhCeHdiRFZadWR6eERa SjFDMlZYdWpDT0pWeHEya2wKakJNOUVUWXVVR3FkNzVBVzJMWHJMdzYrTXVJc0hGQVlBZ1Jy NytLY3dEZ0JBZndoU In-Reply-To: <93463227-33a8-85a0-fd19-8b29b75997f3@yandex.ru> Content-Language: en-US X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-Received-From: 209.51.188.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:178959 Archived-At: On 4/24/20 9:46 AM, Dmitry Gutov wrote: > On 24.04.2020 19:39, Mattias Engdeg=C3=A5rd wrote: >> That is an interesting point. What is the difference between CANNOT an= d SHOULD >> NOT, operationally? To the user, nothing; there is no gain from disobe= ying our >> advice. >=20 > The difference is at runtime, obviously. And the problem is using the w= ords in a > way that differs from other programming languages, for instance. That depends on what other programming languages we're talking about. The current use of 'constant' in the manual corresponds reasonably closely to 'const' objects in C and C++. >> It's useful to have the option to add strong checks, so that (setcar '= (1 . 2) >> 3) throws an error. Then, what used to be SHOULD NOT turns into CANNOT= , but >> the attentive user has no reason to change behaviour. >=20 > *If* we do that, we could call them constants. But I imagine we never w= ill, for > backward compatibility reasons. Emacs core itself modifies these "const= ants" at > runtime in quite a few places, I'm sure. Actually Emacs formerly was more careful about this sort of thing: more o= bjects were constant and Emacs reliably signaled an error if you tried to change= them. If we brought back this feature we'd actually be more backwards-compatibl= e than we already are, at least in some sense. I expect it'd be a good thing to = do if it didn't hurt performance, as it should help reliability/safety a bit.