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1.1 root 1: ;; Copyright (C) 1985, 1986 Free Software Foundation, inc.
2:
3: ;; This file is part of GNU Emacs.
4:
5: ;; GNU Emacs is free software; you can redistribute it and/or modify
6: ;; it under the terms of the GNU General Public License as published by
7: ;; the Free Software Foundation; either version 1, or (at your option)
8: ;; any later version.
9:
10: ;; GNU Emacs is distributed in the hope that it will be useful,
11: ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
12: ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13: ;; GNU General Public License for more details.
14:
15: ;; You should have received a copy of the GNU General Public License
16: ;; along with GNU Emacs; see the file COPYING. If not, write to
17: ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
18:
19:
20: ;; This file is autloaded to handle certain conditions
21: ;; detected by the file-locking code within Emacs.
22: ;; The two entry points are `ask-user-about-lock' and
23: ;; `ask-user-about-supersession-threat'.
24:
25:
26: (put 'file-locked 'error-conditions '(file-locked file-error error))
27:
28: (defun ask-user-about-lock (fn opponent)
29: "Ask user what to do when he wants to edit FILE but it is locked by USER.
30: This function has a choice of three things to do:
31: do (signal 'buffer-file-locked (list FILE USER))
32: to refrain from editing the file
33: return t (grab the lock on the file)
34: return nil (edit the file even though it is locked).
35: You can rewrite it to use any criterion you like to choose which one to do."
36: (discard-input)
37: (save-window-excursion
38: (let (answer)
39: (while (null answer)
40: (message "%s is locking %s: action (s, q, p, ?)? " opponent fn)
41: (let ((tem (let ((inhibit-quit t)
42: (cursor-in-echo-area t))
43: (prog1 (downcase (read-char))
44: (setq quit-flag nil)))))
45: (if (= tem help-char)
46: (ask-user-about-lock-help)
47: (setq answer (assoc tem '((?s . t)
48: (?q . yield)
49: (?\C-g . yield)
50: (?p . nil)
51: (?? . help))))
52: (cond ((null answer)
53: (beep)
54: (message "Please type q, s, or p; or ? for help")
55: (sit-for 3))
56: ((eq (cdr answer) 'help)
57: (ask-user-about-lock-help)
58: (setq answer nil))
59: ((eq (cdr answer) 'yield)
60: (signal 'file-locked (list "File is locked" fn opponent)))))))
61: (cdr answer))))
62:
63: (defun ask-user-about-lock-help ()
64: (with-output-to-temp-buffer "*Help*"
65: (princ "It has been detected that you want to modify a file that someone else has
66: already started modifying in EMACS.
67:
68: You can <s>teal the file; The other user becomes the
69: intruder if (s)he ever unmodifies the file and then changes it again.
70: You can <p>roceed; you edit at your own (and the other user's) risk.
71: You can <q>uit; don't modify this file.")))
72:
73: (put
74: 'file-supersession 'error-conditions '(file-supersession file-error error))
75:
76: (defun ask-user-about-supersession-threat (fn)
77: "Ask a user who is about to modify an obsolete buffer what to do.
78: This function has two choices: it can return, in which case the modification
79: of the buffer will proceed, or it can (signal 'file-supersession (file)),
80: in which case the proposed buffer modification will not be made.
81: You can rewrite this to use any criterion you like to choose which one to do."
82: (discard-input)
83: (save-window-excursion
84: (let (answer)
85: (while (null answer)
86: (message "File has changed on disk; really want to edit the buffer? (y, n or C-h) ")
87: (let ((tem (downcase (let ((cursor-in-echo-area t))
88: (read-char)))))
89: (setq answer
90: (if (= tem help-char)
91: 'help
92: (cdr (assoc tem '((?n . yield)
93: (?\C-g . yield)
94: (?y . proceed)
95: (?? . help))))))
96: (cond ((null answer)
97: (beep)
98: (message "Please type y or n; or ? for help")
99: (sit-for 3))
100: ((eq answer 'help)
101: (ask-user-about-supersession-help)
102: (setq answer nil))
103: ((eq answer 'yield)
104: (signal 'file-supersession
105: (list "File changed on disk" fn))))))
106: (message
107: "File on disk now will become a backup file if you save these changes.")
108: (setq buffer-backed-up nil))))
109:
110: (defun ask-user-about-supersession-help ()
111: (with-output-to-temp-buffer "*Help*"
112: (princ "You want to modify a buffer whose disk file has changed
113: since you last read it in or saved it with this buffer.
114:
115: If you say `y' to go ahead and modify this buffer,
116: you risk ruining the work of whoever rewrote the file.
117: If you say `n', the change you started to make will be aborted.
118:
119: You might consider answering `n', running `M-x revert-buffer' to
120: bring the text in Emacs into accord with what is on disk, and then
121: making the change again.")))
122:
123:
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