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Annotation of 43BSDReno/contrib/emacs-18.55/lisp/userlock.el, revision 1.1

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 distributed in the hope that it will be useful,
        !             6: ;; but WITHOUT ANY WARRANTY.  No author or distributor
        !             7: ;; accepts responsibility to anyone for the consequences of using it
        !             8: ;; or for whether it serves any particular purpose or works at all,
        !             9: ;; unless he says so in writing.  Refer to the GNU Emacs General Public
        !            10: ;; License for full details.
        !            11: 
        !            12: ;; Everyone is granted permission to copy, modify and redistribute
        !            13: ;; GNU Emacs, but only under the conditions described in the
        !            14: ;; GNU Emacs General Public License.   A copy of this license is
        !            15: ;; supposed to have been given to you along with GNU Emacs so you
        !            16: ;; can know your rights and responsibilities.  It should be in a
        !            17: ;; file named COPYING.  Among other things, the copyright notice
        !            18: ;; and this notice must be preserved on all copies.
        !            19: 
        !            20: 
        !            21: ;; This file is autloaded to handle certain conditions
        !            22: ;; detected by the file-locking code within Emacs.
        !            23: ;; The two entry points are `ask-user-about-lock' and
        !            24: ;; `ask-user-about-supersession-threat'.
        !            25: 
        !            26: 
        !            27: (put 'file-locked 'error-conditions '(file-locked file-error error))
        !            28: 
        !            29: (defun ask-user-about-lock (fn opponent)
        !            30:   "Ask user what to do when he wants to edit FILE but it is locked by USER.
        !            31: This function has a choice of three things to do:
        !            32:   do (signal 'buffer-file-locked (list FILE USER))
        !            33:     to refrain from editing the file
        !            34:   return t (grab the lock on the file)
        !            35:   return nil (edit the file even though it is locked).
        !            36: You can rewrite it to use any criterion you like to choose which one to do."
        !            37:   (discard-input)
        !            38:   (save-window-excursion
        !            39:     (let (answer)
        !            40:       (while (null answer)
        !            41:        (message "%s is locking %s: action (s, q, p, ?)? " opponent fn)
        !            42:        (let ((tem (let ((inhibit-quit t)
        !            43:                         (cursor-in-echo-area t))
        !            44:                     (prog1 (downcase (read-char))
        !            45:                            (setq quit-flag nil)))))
        !            46:          (if (= tem help-char)
        !            47:              (ask-user-about-lock-help)
        !            48:            (setq answer (assoc tem '((?s . t)
        !            49:                                      (?q . yield)
        !            50:                                      (?\C-g . yield)
        !            51:                                      (?p . nil)
        !            52:                                      (?? . help))))
        !            53:            (cond ((null answer)
        !            54:                   (beep)
        !            55:                   (message "Please type q, s, or p; or ? for help")
        !            56:                   (sit-for 3))
        !            57:                  ((eq (cdr answer) 'help)
        !            58:                   (ask-user-about-lock-help)
        !            59:                   (setq answer nil))
        !            60:                  ((eq (cdr answer) 'yield)
        !            61:                   (signal 'file-locked (list "File is locked" fn opponent)))))))
        !            62:       (cdr answer))))
        !            63: 
        !            64: (defun ask-user-about-lock-help ()
        !            65:   (with-output-to-temp-buffer "*Help*"
        !            66:     (princ "It has been detected that you want to modify a file that someone else has
        !            67: already started modifying in EMACS.
        !            68: 
        !            69: You can <s>teal the file; The other user becomes the
        !            70:   intruder if (s)he ever unmodifies the file and then changes it again.
        !            71: You can <p>roceed; you edit at your own (and the other user's) risk.
        !            72: You can <q>uit; don't modify this file.")))
        !            73: 
        !            74: (put
        !            75:  'file-supersession 'error-conditions '(file-supersession file-error error))
        !            76: 
        !            77: (defun ask-user-about-supersession-threat (fn)
        !            78:   "Ask a user who is about to modify an obsolete buffer what to do.
        !            79: This function has two choices: it can return, in which case the modification
        !            80: of the buffer will proceed, or it can (signal 'file-supersession (file)),
        !            81: in which case the proposed buffer modification will not be made.
        !            82: You can rewrite this to use any criterion you like to choose which one to do."
        !            83:   (discard-input)
        !            84:   (save-window-excursion
        !            85:     (let (answer)
        !            86:       (while (null answer)
        !            87:        (message "File has changed on disk; really want to edit the buffer? (y, n or C-h) ")
        !            88:        (let ((tem (downcase (let ((cursor-in-echo-area t))
        !            89:                               (read-char)))))
        !            90:          (setq answer
        !            91:                (if (= tem help-char)
        !            92:                    'help
        !            93:                  (cdr (assoc tem '((?n . yield)
        !            94:                                    (?\C-g . yield)
        !            95:                                    (?y . proceed)
        !            96:                                    (?? . help))))))
        !            97:          (cond ((null answer)
        !            98:                 (beep)
        !            99:                 (message "Please type y or n; or ? for help")
        !           100:                 (sit-for 3))
        !           101:                ((eq answer 'help)
        !           102:                 (ask-user-about-supersession-help)
        !           103:                 (setq answer nil))
        !           104:                ((eq answer 'yield)
        !           105:                 (signal 'file-supersession
        !           106:                         (list "File changed on disk" fn))))))
        !           107:       (message
        !           108:         "File on disk now will become a backup file if you save these changes.")
        !           109:       (setq buffer-backed-up nil))))
        !           110: 
        !           111: (defun ask-user-about-supersession-help ()
        !           112:   (with-output-to-temp-buffer "*Help*"
        !           113:     (princ "You want to modify a buffer whose disk file has changed
        !           114: since you last read it in or saved it with this buffer.
        !           115: 
        !           116: If you say `y' to go ahead and modify this buffer,
        !           117: you risk ruining the work of whoever rewrote the file.
        !           118: If you say `n', the change you started to make will be aborted.
        !           119: 
        !           120: You might consider answering `n', running `M-x revert-buffer' to
        !           121: bring the text in Emacs into accord with what is on disk, and then
        !           122: making the change again.")))
        !           123: 
        !           124: 

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