GNU bug report logs - #8948
24.0.50; y-or-n-p doesn't support scroll-o-w like yes-or-no-p

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Message #14 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Deniz Dogan <deniz <at> dogan.se>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#8948: 24.0.50;
	y-or-n-p doesn't support scroll-o-w like yes-or-no-p
Date: Fri, 01 Jul 2011 11:25:03 +0200

On 2011-06-30 21:30, Deniz Dogan wrote:
> On 2011-06-30 16:57, Thierry Volpiatto wrote:
>> Thierry Volpiatto<thierry.volpiatto <at> gmail.com> writes:
>>
>>> Hi,
>>> after discussion about bug#8927, i discover that
>>> from a yes-or-no-p i can scroll-other-window, but not from a
>>> y-or-n-p.
>>
>> This allow scrolling from a y-or-n-p:
>>
>>
>> #+BEGIN_SRC lisp
>> (defun y-or-n-p (prompt)
>> "Ask user a \"y or n\" question. Return t if answer is \"y\".
>> PROMPT is the string to display to ask the question. It should
>> end in a space; `y-or-n-p' adds \"(y or n) \" to it.
>>
>> No confirmation of the answer is requested; a single character is enough.
>> Also accepts Space to mean yes, or Delete to mean no. \(Actually, it uses
>> the bindings in `query-replace-map'; see the documentation of that
>> variable
>> for more information. In this case, the useful bindings are `act',
>> `skip',
>> `recenter', and `quit'.\)
>>
>> Under a windowing system a dialog box will be used if
>> `last-nonmenu-event'
>> is nil and `use-dialog-box' is non-nil."
>> ;; ¡Beware! when I tried to edebug this code, Emacs got into a weird
>> state
>> ;; where all the keys were unbound (i.e. it somehow got triggered
>> ;; within read-key, apparently). I had to kill it.
>> (let ((answer 'recenter))
>> (if (and (display-popup-menus-p)
>> (listp last-nonmenu-event)
>> use-dialog-box)
>> (setq answer
>> (x-popup-dialog t `(,prompt ("yes" . act) ("No" . skip))))
>> (setq prompt (concat prompt
>> (if (eq ?\s (aref prompt (1- (length prompt))))
>> "" " ")
>> "(y or n) "))
>> (while
>> (let* ((key
>> (let ((cursor-in-echo-area t))
>> (when minibuffer-auto-raise
>> (raise-frame (window-frame (minibuffer-window))))
>> (read-key (propertize (if (or (eq answer 'recenter)
>> (eq com 'scroll-other-window)
>> (eq com 'scroll-other-window-down))
>> prompt
>> (concat "Please answer y or n. "
>> prompt))
>> 'face 'minibuffer-prompt)))))
>> (setq answer (lookup-key query-replace-map (vector key) t))
>> (setq com (lookup-key global-map (vector key) t))
>> (cond
>> ((eq com 'scroll-other-window)
>> (with-selected-window (minibuffer-window)
>> (scroll-other-window 1)) t)
>> ((eq com 'scroll-other-window-down)
>> (with-selected-window (minibuffer-window)
>> (scroll-other-window -1)) t)
>> ((memq answer '(skip act)) nil)
>> ((eq answer 'recenter) (recenter) t)
>> ((memq answer '(exit-prefix quit)) (signal 'quit nil) t)
>> (t t)))
>> (ding)
>> (discard-input)))
>> (let ((ret (eq answer 'act)))
>> (unless noninteractive
>> (message "%s %s" prompt (if ret "y" "n")))
>> ret)))
>>
>> #+END_SRC
>>
>
>
> I'm not so sure that's a suitable solution. What if someone wants yet
> another command to work in `y-or-n-p'?
>

Here is an alternative solution which utilizes the current global map if 
the answer is not found in query-replace-map.

I'm not sure this is suitable either since there is no telling what kind 
of interactive commands that can mess things up for the user.



=== modified file 'lisp/subr.el'
--- lisp/subr.el	2011-06-21 08:55:22 +0000
+++ lisp/subr.el	2011-07-01 09:23:35 +0000
@@ -2158,15 +2158,16 @@
 No confirmation of the answer is requested; a single character is enough.
 Also accepts Space to mean yes, or Delete to mean no.  \(Actually, it uses
 the bindings in `query-replace-map'; see the documentation of that 
variable
-for more information.  In this case, the useful bindings are `act', `skip',
-`recenter', and `quit'.\)
+for more information.  If the character is not found within that map, it
+looks in the current global map instead.\)

 Under a windowing system a dialog box will be used if `last-nonmenu-event'
 is nil and `use-dialog-box' is non-nil."
   ;; ¡Beware! when I tried to edebug this code, Emacs got into a weird 
state
   ;; where all the keys were unbound (i.e. it somehow got triggered
   ;; within read-key, apparently).  I had to kill it.
-  (let ((answer 'recenter))
+  (let (answer
+        (valid-answer t))
     (if (and (display-popup-menus-p)
              (listp last-nonmenu-event)
              use-dialog-box)
@@ -2181,7 +2182,7 @@
                   (let ((cursor-in-echo-area t))
                     (when minibuffer-auto-raise
                       (raise-frame (window-frame (minibuffer-window))))
-                    (read-key (propertize (if (eq answer 'recenter)
+                    (read-key (propertize (if valid-answer
                                               prompt
                                             (concat "Please answer y 
or n.  "
                                                     prompt))
@@ -2189,9 +2190,14 @@
             (setq answer (lookup-key query-replace-map (vector key) t))
             (cond
              ((memq answer '(skip act)) nil)
-             ((eq answer 'recenter) (recenter) t)
              ((memq answer '(exit-prefix quit)) (signal 'quit nil) t)
-             (t t)))
+             (t (setq answer (lookup-key (current-global-map) (vector 
key) t))
+                (if (not (commandp answer))
+                    (progn
+                      (setq valid-answer nil)
+                      t)
+                  (call-interactively answer)
+                  (setq valid-answer t)))))
         (ding)
         (discard-input)))
     (let ((ret (eq answer 'act)))

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