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, 10 May 2020 18:57:00 -0700 Organization: UCLA Computer Science Department Message-ID: <4ba236ce-ade0-5cd1-656a-f2df46d67d5f@cs.ucla.edu> References: <9375aaeb-2a9a-b307-c793-0d99328201ea@yandex.ru> <7fe0574a-62ae-94fb-2e55-1a69de6ce828@cs.ucla.edu> <91857438-f44a-90f4-dfe2-a32224ba3994@yandex.ru> <880dc34b-46a9-0149-3c6e-0a951a70125d@cs.ucla.edu> <9c46b93e-a855-0be0-7ab0-50cb8c5cd74d@yandex.ru> <48e90f87-1519-9101-d54b-4bfd81a0c936@yandex.ru> <252d6368-ddea-2f41-b53f-cd927ebc3d1d@cs.ucla.edu> <43d93102-d361-f64b-971b-909418b89fca@yandex.ru> <2ca64f28-1255-4135-6e45-0f0e12b9e72d@cs.ucla.edu> <0c7570cb-bf52-a617-bf54-27a47c54e04a@cs.ucla.edu> <04298f7d-f2c0-5186-57d3-522e3d886166@cs.ucla.edu> <88af48c6-bc39-6ab0-59ec-7d537f2d375d@yandex.ru> <41d69e2e-561f-743a-e1f0-282b2e22b66c@cs.ucla.edu> Mime-Version: 1.0 Content-Type: text/plain; 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Sun, 10 May 2020 18:57:01 -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 bdnCwAKv-bQJ; Sun, 10 May 2020 18:57:01 -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 E8D081600C7; Sun, 10 May 2020 18:57:00 -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: Content-Language: en-US X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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:180040 Archived-At: On 5/10/20 5:44 PM, Dmitry Gutov wrote: > "Indeed"? Indeed yes. :-) > The changing "mutability" status is imaginary, however. It's part of a spec. Not every constraint in a spec needs to be enforced directly by the implementation. That doesn't mean these constraints are "= imaginary". > This also requires the reader to read the manual without missing a refe= rence. A > regular person would not understand your meaning of "mutable" without f= ollowing > the reference to {Mutability}. If a paragraph says "mutable" and has a cross-reference to the "Mutabilit= y" section, that's good enough. This is a reference manual, not a tutorial, = and we can assume a reasonable level of competence on the part of the reader. > Does is ignore the possibility of the example in the previous version, = then? I don't understand this remark. > I'm trying to point out the incompatibility with the regular meanings o= f the > words used. >> Because it's not an accurate statement of the problem. The set of obje= cts that >> might be shared differs from the set of objects that should not change= . The >> Mutability node focuses on the latter set of objects, and gives the fo= rmer as an >> example but it is not the only sort of object that should not change. >=20 > But if we don't mention such cases in "Mutability", where do we cover t= hem? Fair enough. I added an example of such a case to "Mutability" in the pro= posal in my most-recent email (Bug#40671#441). > +(let* ((x (list 0.5)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 (y (eval (list 'quote x)))) > +=C2=A0 (setcar x 1.5) ;; The program should not do this. > +=C2=A0 y) >=20 > Why is this a problem? Do we expect this it could lead to a segfault? Probably not a segfault in the current implementation, but the behavior i= sn't defined. And we don't want the behavior to be defined, as that would proh= ibit some optimizations that may be coming down the road.