Re: binding c-h in isearch

[Lennart Borgman (gmail)]

Lennart Borgman (gmail) wrote:
> address@hidden wrote:
> > It is difficult to remmeber all nice features of isearch.
> > Would it be possible to bind c-h to isearch-mode-help in isearch?
> >
> > This is done in isearch+.el by Drew Adams.
>
> I think you are right. Beside what Drew have I have a patch for this 
> (which is part of my patches in the patched version of Emacs+EmacsW32).
>
> However I have began to rethink how such help could be implemented. 
> There are other rather similar cases. In tabkey2.el (see EmacsWiki) I 
> also needed to implement some specific help. This is what I did there:
>
> - When the user hits the help key (f1/C-h) a message saying:
>
>   "Type a char for Emacs help. Or, wait for Tab completion help"
>
> - If the response is k or c then specific keybindings valid during tab 
> completion is shown.
>
> This way the user can have access to both a specific help and the usual 
> Emacs help.


I have attached a quick port of the idea above from tabkey2.el to 
isearch.el. There are two versions of help here:

- f1: is the suggestion above.
- C-h: just shows the isearch-mode help


In the f1 version I do not know what to do with the messages in the echo 
area after entering c or k (isearch is still active).
Index: isearch.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/isearch.el,v
retrieving revision 1.315
diff -u -b -r1.315 isearch.el
--- isearch.el  16 Mar 2008 17:44:11 -0000      1.315
+++ isearch.el  16 Apr 2008 22:26:43 -0000
@@ -391,6 +391,8 @@
     ;; Turned off because I find I expect to get the global definition--rms.
     ;; ;; Instead bind C-h to special help command for isearch-mode.
     ;; (define-key map "\C-h" 'isearch-mode-help)
+    (define-key map "\C-h" 'isearch-mode-help)
+    (define-key map [(f1)] 'isearch-maybe-mode-help)
 
     (define-key map "\M-n" 'isearch-ring-advance)
     (define-key map "\M-p" 'isearch-ring-retreat)
@@ -629,10 +631,46 @@
 
 
 (defun isearch-mode-help ()
+  "Show isearch mode help."
   (interactive)
   (describe-function 'isearch-forward)
+  (with-current-buffer (help-buffer)
+    (let ((inhibit-read-only t))
+      (insert (substitute-command-keys
+               "To scroll help use \\[scroll-other-window-down] and 
\\[scroll-other-window].\n\n"))))
   (isearch-update))
 
+(defun isearch-maybe-mode-help ()
+  "Maybe show isearch mode help."
+  (interactive)
+  (let ((invoked-by-f1 (equal (this-command-keys-vector) [f1]))
+        normal-help
+        (wait-time 4))
+    (when invoked-by-f1
+      (with-timeout (wait-time (setq normal-help nil))
+        (setq normal-help
+              (read-char
+               (propertize
+                (format
+                 (concat "Type a char for Emacs help."
+                         " Or, wait %.0d seconds for isearch help: ")
+                 wait-time)
+                'face 'highlight)
+               nil))))
+    (case normal-help
+      ((nil)
+       ;;(message "Tab completion state help")
+       ;;(describe-function 'tabkey2-show-completion-state-help)
+       (isearch-mode-help)
+       )
+      (?c
+       (call-interactively 'describe-key-briefly))
+      (?k
+       (call-interactively 'describe-key))
+      (t
+       (isearch-mode -1)
+       (setq unread-command-events (append (this-command-keys) nil))))))
+
 
 ;; isearch-mode only sets up incremental search for the minor mode.
 ;; All the work is done by the isearch-mode commands.
@@ -1758,6 +1796,18 @@
          ((eq search-exit-option 'edit)
           (apply 'isearch-unread keylist)
           (isearch-edit-string))
+          ;; Always scroll other window if help buffer
+          ((let ((binding (key-binding key))
+                 other-buffer-is-help)
+             (when (or (eq binding 'scroll-other-window-down)
+                       (eq binding 'scroll-other-window))
+               (save-selected-window
+                 (other-window 1)
+                 (setq other-buffer-is-help (equal (buffer-name) "*Help*")))
+               (when other-buffer-is-help
+                 (command-execute binding)
+                 (isearch-update)
+                 t))))
           ;; Handle a scrolling function.
           ((and isearch-allow-scroll
                 (progn (setq key (isearch-reread-key-sequence-naturally 
keylist))
@@ -2027,10 +2077,12 @@
                   (if isearch-forward "" " backward")
                   (if current-input-method
                       (concat " [" current-input-method-title "]: ")
-                    ": ")
-                  )))
-    (propertize (concat (upcase (substring m 0 1)) (substring m 1))
-               'face 'minibuffer-prompt)))
+                     ": ")))
+        m2)
+    (setq m2 (apply 'propertize
+                    (concat (upcase (substring m 0 1)) (substring m 1))
+                    minibuffer-prompt-properties))
+    (propertize m2 'read-only nil)))
 
 (defun isearch-message-suffix (&optional c-q-hack ellipsis)
   (concat (if c-q-hack "^Q" "")