bug#32643: 26; minor-mode variables

[Drew Adams <drew.adams@oracle.com>]

> > > Most probably, historical accidents.  But even finding that out is a
> > > non-trivial amount of work.
> >
> > `auto-fill-mode' has already been identified. Let this bug report serve
> > (at least) to ask that Emacs set an `auto-fill-mode' mode variable.
> 
> You've changed the subject by eliding the context.  The above was an
> answer to your question why some modes have variables while others
> don't.

Yes, it was. And my redaction of the text just before it didn't
 change anything in that regard. If you think it did, please
elaborate.

> As for auto-fill-mode, can you tell why it is important to have a
> variable there?  What cannot you do without that variable?

No, according to the convention the shoe is on the other foot.
Why should it not have a variable? That's the convention.
Why should `auto-fill-mode' be an exception? The fact that
there are some exceptions is no argument for why `a-f-m'
should be one of them.

Plus, you're setting a high bar: you ask what is _impossible to
do_ without the variable. If you insist on putting the shoe on
my foot then the only somewhat reasonable question is how
might it be useful to have the variable - not what is impossible (!)
to do without it.

Anyway, if you insist on asking for a possible use... One answer
is the same as for any other variable:

You can do `C-h v auto-fill-mode' to check whether it is on.
Minor modes do not necessarily have mode-line lighters.
And even in a customized mode-line that shows no lighters that
will tell you whether the mode is on.

Again, why would you _not_ want to have such a variable?

> > > I think the manual already does what you want, it just doesn't say
> > > this is a bug (because it isn't, IMO).
> >
> > The manual says nothing, AFAICT, that provides guidance about when
> > a mode should not or need not have a variable. Based on what it does
> > say, each mode "should" have a variable. Is that your point?
> 
> My point is that the manual recommends that there be a variable.

No one disagrees that that is the case.

> > In that case, perhaps we should remove the text about some existing
> > modes not respecting this "should" - especially if that is only by
> > historical accident.
> 
> If we remove that, we will have no way to respond to bug reports
> requesting that all modes shall have a variable.

Huh? Why can't you respond to such a report? Or do you think that
the manual stating only that some do and some don't provides an
excuse for doing nothing in that regard? That doesn't follow.

> > Keeping the text suggests that there is some good reason why some
> > modes do not have variables.
> 
> There's no such suggestion, it's just a statement of a fact.

Why is that fact stated? Is it really to have a way to respond to
bug reports that ask to follow the convention, by saying that
the convention doesn't apply to some modes (without saying
which or why or...)? That's the only reason you've given, so far.