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Apropos commands and regexps
From: |
Kim F. Storm |
Subject: |
Apropos commands and regexps |
Date: |
12 May 2002 02:57:20 +0200 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.2.50 |
I was thinking about the use of regexps in connection with the various
apropos commands.
We often advise new users to use e.g. C-h a or M-x apropos (also
accessible through the Help menu).
However, these commands prompts like this:
Apropos command (regexp):
which may be nonsense to some novice users.
Wouldn't it be simpler (for a novice user -- and for advanced users
too) to simply write one or more words (substrings) and then search
for all combinations of those words (substrings) in the relevant list.
E.g. C-h a open file RET would find any matching
open.*file and file.*open
BTW, this obvious example doesn't find `find-file' :-(
Maybe we should have a defalias open-file -> find-file ?
Of course, if the input is already a regexp (e.g. if it does not
contain any spaces), it should be used directly. Below is a patch
to show the concept:
Index: apropos.el
===================================================================
RCS file: /cvs/emacs/lisp/apropos.el,v
retrieving revision 1.84
diff -c -r1.84 apropos.el
*** apropos.el 4 May 2002 14:51:16 -0000 1.84
--- apropos.el 11 May 2002 23:55:10 -0000
***************
*** 122,127 ****
--- 122,130 ----
(defvar apropos-regexp nil
"Regexp used in current apropos run.")
+ (defvar apropos-orig-regexp nil
+ "Regexp as entered by user.")
+
(defvar apropos-files-scanned ()
"List of elc files already scanned in current run of
`apropos-documentation'.")
***************
*** 219,224 ****
--- 222,245 ----
(and label button)))
+ (defun apropos-rewrite-regexp (regexp)
+ "Rewrite a list of words to a regexp matching all permutations.
+ If REGEXP is already a regexp, don't modify it."
+ (setq apropos-orig-regexp regexp)
+ (if (and (string-match " " regexp)
+ (string-equal (regexp-quote regexp) regexp))
+ ;; We don't actually make a regexp matching all permutations.
+ ;; Instead, for e.g. "a b c", we make a regexp matching
+ ;; any combination of two or more words like this:
+ ;; (a|b|c).*(a|b|c) which may give some false matches,
+ ;; but as long as it also gives the right ones, that's ok.
+ (let ((words (split-string regexp "[ \t]+"))
+ res)
+ (dolist (w words)
+ (setq res (concat (or res "\\(") (if res "\\|" "") w)))
+ (concat res "\\).*" res "\\)"))
+ regexp))
+
;;;###autoload
(define-derived-mode apropos-mode fundamental-mode "Apropos"
"Major mode for following hyperlinks in output of apropos commands.
***************
*** 262,267 ****
--- 283,289 ----
"or function ")
"(regexp): "))
current-prefix-arg))
+ (setq apropos-regexp (apropos-rewrite-regexp apropos-regexp))
(let ((message
(let ((standard-output (get-buffer-create "*Apropos*")))
(print-help-return-message 'identity))))
***************
*** 304,309 ****
--- 326,332 ----
show unbound symbols and key bindings, which is a little more
time-consuming. Returns list of symbols and documentation found."
(interactive "sApropos symbol (regexp): \nP")
+ (setq apropos-regexp (apropos-rewrite-regexp apropos-regexp))
(setq apropos-accumulator
(apropos-internal apropos-regexp
(and (not do-all)
***************
*** 371,376 ****
--- 394,400 ----
at the function and at the names and values of properties.
Returns list of symbols and values found."
(interactive "sApropos value (regexp): \nP")
+ (setq apropos-regexp (apropos-rewrite-regexp apropos-regexp))
(or do-all (setq do-all apropos-do-all))
(setq apropos-accumulator ())
(let (f v p)
***************
*** 397,402 ****
--- 421,427 ----
bindings.
Returns list of symbols and documentation found."
(interactive "sApropos documentation (regexp): \nP")
+ (setq apropos-regexp (apropos-rewrite-regexp apropos-regexp))
(or do-all (setq do-all apropos-do-all))
(setq apropos-accumulator () apropos-files-scanned ())
(let ((standard-input (get-buffer-create " apropos-temp"))
***************
*** 590,596 ****
If SPACING is non-nil, it should be a string;
separate items with that string."
(if (null apropos-accumulator)
! (message "No apropos matches for `%s'" apropos-regexp)
(setq apropos-accumulator
(sort apropos-accumulator (lambda (a b)
(string-lessp (car a) (car b)))))
--- 615,621 ----
If SPACING is non-nil, it should be a string;
separate items with that string."
(if (null apropos-accumulator)
! (message "No apropos matches for `%s'" apropos-orig-regexp)
(setq apropos-accumulator
(sort apropos-accumulator (lambda (a b)
(string-lessp (car a) (car b)))))
--
Kim F. Storm <address@hidden> http://www.cua.dk
- Apropos commands and regexps,
Kim F. Storm <=