John Wiegley <jwiegley@gmail.com> schrieb am Di., 26. Sep. 2017 um
20:55 Uhr:

> >>>>> Drew Adams <drew.adams@oracle.com> writes:
>
> > Good luck with such a guideline. The state of an Emacs session is _never_
> > exactly the same after each time you turn on a mode - any mode, any
> session.
> > So many things change...
>
> I think we can reduce the scope of what we're saying:
>
> The statement I made only applies if the command is called in immediate
> succession. That is, the function is *itself* idempotent; it doesn't
> guarantee
> that intervening effects are somehow negated.
>
> That is, the following should be functionally equivalent:
>
>     (foo-mode 1)
>     (progn (foo-mode 1) (foo-mode 1))
>
> I don't see what great difficulty this poses. If a mode author is doing
> thing
> inside `foo-mode' like changing the system or the disk, that's exactly the
> sort of thing our guideline seeks to prevent.
>

Given that all current and past maintainers seem to agree, how about the
following patch for the Lisp manual?