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: Sun, 26 Apr 2020 18:49:23 -0700 Organization: UCLA Computer Science Department Message-ID: <6d1015da-0dc1-376c-f84b-5e3ee3149213@cs.ucla.edu> References: <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> <969b3497-0afd-d104-6792-d744d31548fa@cs.ucla.edu> <2935ec84-bdea-2e20-01b9-8ed08cc61c6c@yandex.ru> <669981e5-f601-5c18-1a8b-ee316ad001ec@cs.ucla.edu> <4b8b7e98-029e-58ac-59ff-6cd984b7eb85@yandex.ru> <530d3597-aaaa-f019-bafa-8229d13e7248@yandex.ru> <60b88f52-c50d-c57a-9ce5-495e6157d36e@cs.ucla.edu> <0721d8c1-4fe3-335c-7dbc-171487cb648a@yandex.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="117349"; 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 , Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= , ke.vigouroux@laposte.net, 40671@debbugs.gnu.org, Richard Stallman To: Dmitry Gutov Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Apr 27 03:50:15 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 1jSsuV-000URC-9M for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 27 Apr 2020 03:50:15 +0200 Original-Received: from localhost ([::1]:50102 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jSsuU-0001TJ-0w for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 26 Apr 2020 21:50:14 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:57834) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jSsuJ-0001Su-7R for bug-gnu-emacs@gnu.org; Sun, 26 Apr 2020 21:50:03 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jSsuI-0003dR-OO for bug-gnu-emacs@gnu.org; Sun, 26 Apr 2020 21:50:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:51950) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jSsuI-0003dJ-CS for bug-gnu-emacs@gnu.org; Sun, 26 Apr 2020 21:50:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jSsuI-0007FC-9S for bug-gnu-emacs@gnu.org; Sun, 26 Apr 2020 21:50:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Paul Eggert Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 27 Apr 2020 01:50:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 40671 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: patch Original-Received: via spool by 40671-submit@debbugs.gnu.org id=B40671.158795217427800 (code B ref 40671); Mon, 27 Apr 2020 01:50:02 +0000 Original-Received: (at 40671) by debbugs.gnu.org; 27 Apr 2020 01:49:34 +0000 Original-Received: from localhost ([127.0.0.1]:35263 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jSstp-0007EJ-LA for submit@debbugs.gnu.org; Sun, 26 Apr 2020 21:49:33 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:47172) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jSstn-0007E4-4r for 40671@debbugs.gnu.org; Sun, 26 Apr 2020 21:49:31 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 6852A16008E; Sun, 26 Apr 2020 18:49:24 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id gG3iJ2wBe-YH; Sun, 26 Apr 2020 18:49:23 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 9BA521600D1; Sun, 26 Apr 2020 18:49:23 -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 sfjMD31wKV_V; Sun, 26 Apr 2020 18:49:23 -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 5F35F16008E; Sun, 26 Apr 2020 18:49:23 -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: <0721d8c1-4fe3-335c-7dbc-171487cb648a@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:179120 Archived-At: On 4/26/20 5:53 PM, Dmitry Gutov wrote: > is the behavior of "literal objects" in Emacs > Lisp undefined when one tries to modify them? Yes. >>> Do you have an example of a version of Emacs where this behavior was different? >> >> Emacs 26. > > Sorry, I don't have an Emacs 26 at hand. Should 25 suffice? Yes. Just tried this in > IELM: > > ELISP> (setq a '(1 . 2)) > (1 . 2) > > ELISP> (setcdr a 3) > 3 (#o3, #x3, ?\C-c) > ELISP> a > (1 . 3) Yes, the behavior is undefined in Emacs 25 too. Undefined means that the behavior you describe is allowed - in this instance you modified the "constant" and got away with it. > In Ruby, we also have "constants" and we sometimes laugh about being able to > change them. And yet, there also you can't do it by accident. I suppose it depends on what one means by "accident". :-) Perhaps we could agree that accidents, whatever they are, happen more often in C.... > We better warn against modifying any values that are part of a "literal object" > anywhere. That's what the emacs-27 doc does, or at least tries to do.