Question

EDIT: I understand there is keyboard-quit (which is normally bound to C-g); but I’m more interested to know about how one deals with editing functions that come with Emacs (like in this case). I run into this kind of situations from time to time when I want to change just a little bit of some build-in functions.

In emacs, when you hit M-ESC ESC (or ESC three times), you can get out of a lots of situations like transient-mark, etc. But I habitually hit the escape key (I actually remap this to a single hit of the escape key) more than I intended, and that ends up killing my windows configuration, which is quite annoying. The function keyboard-escape-quit is defined in simple.el:

(defun keyboard-escape-quit ()   'Exit the current \'mode\' (in a generalized sense of the word). This command can exit an interactive command such as `query-replace', can clear out a prefix argument or a region, can get out of the minibuffer or other recursive edit, cancel the use of the current buffer (for special-purpose buffers), or go back to just one window (by deleting all but the selected window).'   (interactive)   (cond ((eq last-command 'mode-exited) nil)     ((> (minibuffer-depth) 0)      (abort-recursive-edit))     (current-prefix-arg      nil)     ((and transient-mark-mode mark-active)      (deactivate-mark))     ((> (recursion-depth) 0)      (exit-recursive-edit))     (buffer-quit-function      (funcall buffer-quit-function))     ((not (one-window-p t))      (delete-other-windows))     ((string-match '^ \\*' (buffer-name (current-buffer)))      (bury-buffer)))) 

And I can see that I don’t want the lines:

    ((not (one-window-p t))      (delete-other-windows)) 

But what is the best way to modify this function? I can see only two ways: 1) modify simple.el 2) copy this function to my .emacs file and do the modifications there. Both ways are not really good; ideally I would like to see something on the line of defadvice, but I can’t see how I can do it in this case.

Answer 1

You could use around advice and redefine the offending function to do what you want (i.e. one-window-p should always return t):

(defadvice keyboard-escape-quit (around my-keyboard-escape-quit activate)   (let (orig-one-window-p)     (fset 'orig-one-window-p (symbol-function 'one-window-p))     (fset 'one-window-p (lambda (&optional nomini all-frames) t))     (unwind-protect         ad-do-it       (fset 'one-window-p (symbol-function 'orig-one-window-p))))) 

This kind of acts like a (let …) but has to be more complicated because you need to override a function for a limited scope instead of a variable.