Re: turning on minor modes from hooks

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> Stephen has long advocated that non-interactive invocation of mode
   ^^^^^^^
Was that meant to be me?

>> commands should always turn on the mode instead of toggling.

> So interactively a nil arg will toggle, but in Lisp a nil arg will
> turn it on?  And just why is that a great idea?

No:  currently, minor modes defined with `define-minor-mode' will never
receive nil when invoked interactively.  They'll either get a prefix
arg, or the symbol `toggle'.

The patch below would change define-minor-mode as suggested.


        Stefan


--- lisp/emacs-lisp/easy-mmode.el	2009-01-05 10:18:22 +0000
+++ lisp/emacs-lisp/easy-mmode.el	2009-07-24 02:11:35 +0000
@@ -225,12 +225,7 @@
                  (cond
                   ((eq arg 'toggle) (not ,mode))
                   (arg (> (prefix-numeric-value arg) 0))
-                  (t
-                   (if (null ,mode) t
-                     (message
-                      "Toggling %s off; better pass an explicit argument."
-                      ',mode)
-                     nil))))
+		(t)))
            ,@body
            ;; The on/off hooks are here for backward compatibility only.
            (run-hooks ',hook (if ,mode ',hook-on ',hook-off))