Re: [matt@mundell.ukfsn.org: momentary-string-display input passing]

[Matthew Mundell <matt@mundell.ukfsn.org>]

Richard Stallman <rms@gnu.org> writes:

> This change looks basically reasonable to me, except I don't think
> that an error is the right thing to do when the user types a function
> key or clicks the mouse instead of typing the specified key.  I think
> those should just be ignored, the way other input characters are
> ignored.
>
> Would someone like to make that change and install this?

The change does ignore such errors.  They are caught by the
condition-case around read-char.  A stray string in the condition case
handler's body makes the handler look like a call to error.  It may be
that I left the string there when turning an older call to error into
the condition case.

A new patch and a change log are below.

> From: Matthew Mundell <matt@mundell.ukfsn.org>
> Subject: momentary-string-display input passing
> To: emacs-pretest-bug <emacs-pretest-bug@gnu.org>
> Date: 17 Feb 2004 23:15:12 +0000
>
> The CVS Elisp manual has the following example for
> momentary-string-display.
>
> (momentary-string-display
>  "**** Important Message! ****"
>  (point) ?\r
>  "Type RET when done reading")
>
> The idea seems to be that an Enter in response will only remove the
> message.  However, evaluating the form (in the CVS Emacs) and pressing
> Enter in response also results in the insertion of a newline.
>
> The Enter key press is read with `read-event', which returns the
> symbol `return', which is different from ?\r.
>
> Perhaps the following change to momentary-string-display will be of
> help.  It uses read-char when the parameter to be matched, EXIT-CHAR,
> is a character.  It would need additions to handle mouse events.
>
> ===================================================================
> RCS file: /cvsroot/emacs/emacs/lisp/subr.el,v
> retrieving revision 1.379
> diff -c -r1.379 subr.el
> *** subr.el	16 Feb 2004 19:40:07 -0000	1.379
> - --- subr.el	17 Feb 2004 18:34:04 -0000
> ***************
> *** 1455,1463 ****
>   		  (recenter 0))))
>   	  (message (or message "Type %s to continue editing.")
>   		   (single-key-description exit-char))
> ! 	  (let ((char (read-event)))
> ! 	    (or (eq char exit-char)
> ! 		(setq unread-command-events (list char)))))
>         (if insert-end
>   	  (save-excursion
>   	    (delete-region pos insert-end)))
> - --- 1455,1475 ----
>   		  (recenter 0))))
>   	  (message (or message "Type %s to continue editing.")
>   		   (single-key-description exit-char))
> ! 	  (let (char)
> ! 	    (if (integerp exit-char)
> ! 		(condition-case nil
> ! 		    (progn
> ! 		      (setq char (read-char))
> ! 		      (or (eq char exit-char)
> ! 			  (setq unread-command-events (list char))))
> ! 		  (error "Non-character input-event"
> ! 			 ;; character type exit-char will differ from this event
> ! 			 (setq unread-command-events (list char))))
> ! 	      ;; assume exit-char an event
> ! 	      (setq char (read-event))
> ! 	      (or (eq char exit-char)
> ! 		  (eq char (event-convert-list exit-char))
> ! 		  (setq unread-command-events (list char))))))
>         (if insert-end
>   	  (save-excursion
>   	    (delete-region pos insert-end)))
>

2004-03-26  Matthew Mundell  <matt@mundell.ukfsn.org>

	* subr.el (momentary-string-display): If EXIT-CHAR is a character
	then read input using read-char, catching any error resulting from
	the input of an event.  Otherwise read with read-event, comparing
	EXIT-CHAR to the input both as a character and an event
	description list.  Doc updated to match.


===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/subr.el,v
diff -u -r1.379 subr.el
--- lisp/subr.el	16 Feb 2004 19:40:07 -0000	1.379
+++ lisp/subr.el	26 Mar 2004 17:08:41 -0000
@@ -1423,9 +1423,11 @@

 (defun momentary-string-display (string pos &optional exit-char message)
   "Momentarily display STRING in the buffer at POS.
-Display remains until next character is typed.
-If the char is EXIT-CHAR (optional third arg, default is SPC) it is swallowed;
-otherwise it is then available as input (as a command if nothing else).
+Display remains until next event is input.
+Optional third arg EXIT-CHAR can be a character, event or event
+description list.  EXIT-CHAR defaults to SPC.  If the input is
+EXIT-CHAR it is swallowed; otherwise it is then available as
+input (as a command if nothing else).
 Display MESSAGE (optional fourth arg) in the echo area.
 If MESSAGE is nil, instructions to type EXIT-CHAR are displayed there."
   (or exit-char (setq exit-char ?\ ))
@@ -1455,9 +1457,23 @@
 		  (recenter 0))))
 	  (message (or message "Type %s to continue editing.")
 		   (single-key-description exit-char))
-	  (let ((char (read-event)))
-	    (or (eq char exit-char)
-		(setq unread-command-events (list char)))))
+	  (let (char)
+	    (if (integerp exit-char)
+		(condition-case nil
+		    (progn
+		      (setq char (read-char))
+		      (or (eq char exit-char)
+			  (setq unread-command-events (list char))))
+		  (error
+		   ;; `exit-char' is a character, hence it differs
+		   ;; from char, which is an event.
+		   (setq unread-command-events (list char))))
+	      ;; `exit-char' can be an event, or an event description
+	      ;; list.
+	      (setq char (read-event))
+	      (or (eq char exit-char)
+		  (eq char (event-convert-list exit-char))
+		  (setq unread-command-events (list char))))))
       (if insert-end
 	  (save-excursion
 	    (delete-region pos insert-end)))