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1 ;; -*-Emacs-Lisp-*-
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2 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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3 ;;
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4 ;; File: efs-ovwrt.el
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5 ;; Release: $efs release: 1.15 $
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6 ;; Version: #Revision: 1.2 $
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7 ;; RCS:
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8 ;; Description: Utilities for overwriting functions with new definitions.
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9 ;; Author: Andy Norman <ange@hplb.hpl.hp.com>
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10 ;;
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11 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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12
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13 ;;; Although used by efs, these utilities could be of general use to other
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14 ;;; packages too. Keeping them separate from the main efs program
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15 ;;; makes it easier for other programs to require them.
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16
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17 (provide 'efs-ovwrt)
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42
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18 (eval-when-compile
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19 (condition-case nil
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20 (require 'advice)
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21 (error)))
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22
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22
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23 (defconst efs-ovwrt-version
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24 (concat (substring "$efs release: 1.15 $" 14 -2)
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25 "/"
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26 (substring "#Revision: 1.2 $" 11 -2)))
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27
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28 (defvar efs-overwrite-fmt
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29 "Note: This function has been modified to work with %s.")
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30
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31 ;; Make the byte compiler happy.
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32 (defvar file-name-handler-alist)
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33 (defvar inhibit-file-name-handlers)
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34 (defvar inhibit-file-name-operation)
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35
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36 (defun efs-safe-documentation (fun)
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37 "A documentation function that isn't quite as fragile."
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38 (condition-case ()
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39 (documentation fun)
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40 (error nil)))
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41
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42 (defun efs-overwrite-fn (package fun &optional newfun)
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43 "Overwrites a function with a new definition from PACKAGE.
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44 PACKAGE should be a string. The the function to be overwritten is FUN.
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45 The new definition is obtained from the optional NEWFUN. If ommitted,
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46 NEWFUN is taken to be PACKAGE-FUN. The original definition is stored in
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47 PACKAGE-real-FUN. The original documentation is placed on the new
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48 definition suitably augmented."
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49 (let* ((name (symbol-name fun))
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50 (saved (intern (concat package "-real-" name)))
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51 (new (or newfun (intern (concat package "-" name))))
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52 (nfun (symbol-function new))
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53 (exec-directory (if (or (equal (nth 3 command-line-args) "dump")
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54 (equal (nth 4 command-line-args) "dump"))
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55 "../etc/"
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56 exec-directory)))
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57
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58 (while (symbolp nfun)
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59 (setq nfun (symbol-function nfun)))
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60
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61 ;; Interpose the new function between the function symbol and the
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62 ;; original definition of the function symbol AT TIME OF FIRST LOAD.
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63 ;; We must only redefine the symbol-function of FUN the very first
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64 ;; time, to avoid blowing away stuff that overloads FUN after this.
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65
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66 ;; We direct the function symbol to the new function symbol
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67 ;; rather than function definition to allow reloading of this file or
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68 ;; redefining of the individual function (e.g., during debugging)
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69 ;; later after some other code has been loaded on top of our stuff.
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70
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71 (or (fboundp saved)
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72 (let ((advised-p (and (featurep 'advice)
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73 (ad-is-advised fun))))
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74 (if advised-p (ad-deactivate fun))
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75 (fset saved (symbol-function fun))
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76 (fset fun new)
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77 (if advised-p (ad-activate fun))))
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78
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79 ;; Rewrite the doc string on the new function. This should
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80 ;; be done every time the file is loaded (or a function is redefined),
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81 ;; because the underlying overloaded function may have changed its doc
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82 ;; string.
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83
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84 (let* ((doc-str (efs-safe-documentation saved))
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85 (ndoc-str (concat doc-str (and doc-str "\n")
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86 (format efs-overwrite-fmt package))))
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87
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88 (cond ((listp nfun)
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89 ;; Probe to test whether function is in preloaded read-only
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90 ;; memory, and if so make writable copy:
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91 (condition-case nil
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92 (setcar nfun (car nfun))
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93 (error
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94 (setq nfun (copy-sequence nfun)) ; shallow copy only
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95 (fset new nfun)))
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96 (let ((ndoc-cdr (nthcdr 2 nfun)))
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97 (if (stringp (car ndoc-cdr))
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98 ;; Replace the existing docstring.
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99 (setcar ndoc-cdr ndoc-str)
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100 ;; There is no docstring. Insert the overwrite msg.
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101 (setcdr ndoc-cdr (cons (car ndoc-cdr) (cdr ndoc-cdr)))
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102 (setcar ndoc-cdr (format efs-overwrite-fmt package)))))
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103 (t
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104 ;; it's an emacs19 compiled-code object
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105 (let ((new-code (append nfun nil))) ; turn it into a list
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106 (if (nthcdr 4 new-code)
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107 (setcar (nthcdr 4 new-code) ndoc-str)
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108 (setcdr (nthcdr 3 new-code) (cons ndoc-str nil)))
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109 (fset new (apply 'make-byte-code new-code))))))))
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110
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111
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112 ;;; end of efs-ovwrt.el
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