Re: toggling a minor mode should not tell Customize that the value has been set

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

>> Because M-x foo-mode RET on such global minor-modes isn't much different
>> from M-x customize-variable RET foo-mode RET .... -> Set for
>> current session.
> "isn't much different"  How so? What do you mean by that?

It has the same user-visible effect of enabling/disabling the mode in
the current session.

> But _why_ should they be treated similarly? That is the question.

Because they have the same effect in all other respects.

> Logically and a priori, it isn't much the _same_, I'd say.

In which way is it different?

>> > What was the rationale behind this behavior? Why should toggling
>> 
>> The rationale is that Custom does not like it when Elisp code modifies
>> a defcustom behind its back.

> Modifies a defcustom? What does that mean?

"Modifies a variable that's defined via defcustom".

> Changing the value of a variable that happens to be defined by defcustom is

Right, so you did understand ;-)

> Why should toggling a minor mode be tantamount to customizing its variable?

You mean "when done interactively"?
Well that's what this thread is trying to explain, isn't it?

> And if it should for some reason, then why distinguish between global and
> local modes in this regard?

Simple: local modes are not defined via defcustom.

>> If we don't do it, then Custom will simply tell you that the variable
>> was set outside of Custom and that saving the var may hence not have
>> the expected effect.
> But that's what happened: the value was changed outside Customize.

Who says?

> If you ask Customize for what was changed outside Customize, this variable
> should show up.  But if you ask Customize for what was customized but not
> saved (`customize-customized'), this should not show up.

Why?  What would be the benefit?

> Why should toggling a mode variable be considered the same as
> customizing it?

Again, because "they have the same effect in all other respects".

>> > A user should be able to use `customize-customized' (including
>> > perhaps in `kill-emacs-query-functions') to see what s?he has
>> > customized and might want to save.
>> 
>> Exactly, after trying our M-x iswtchb-mode RET she may very much like to
>> see that iswitchb-mode is now eabled and that she could save it so that
>> it's enabled next time around.

> "May?" This design is based only on that _possibility_?

No.  It was in response to some request.  I can't remember the details
of it, but I can assure you that it wouldn't have crossed my mind to do
that if it weren't for someone complaining about the "changed outside
Customize".

> It think it is far more likely that someone will toggle a mode on and off
> occasionally, without that action implying that s?he would want to save its
> last value.

Nobody complained about this behavior since it was introduced (in
Emacs-21 IIRC), so I don't know about "far more likely" or about the
importance of this detail.


        Stefan