bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Drew Adams]

The Value Menu in Customize wrongly give the user no way to specify an
arbitrary predicate, and wrongly gives the impression that the option
value must be one of the two predicates presented (or nil).

The :type spec should provide a third possibility for the menu: an
arbitrary function (which is used as a predicate).

That menu item's :tag should make clear that the function is used as
a predicate: nil means..., non-nil means....

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-09-20 on LEG570
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking 'CFLAGS=-O0 -g3' CPPFLAGS=-DGLYPH_DEBUG=1'

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Drew Adams]

Also, the doc should not just say that the predicate "should be a
predicate function such as `yes-or-no-p'. That is confusing and not
very meaningful.  What does it mean to be a predicate "such as
`yes-or-no-p'?

It should say that it is a function that is used as a predicate.
It should say what true and false return values mean (what they do).
And it should say that the function must accept at least one argument.

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> Also, the doc should not just say that the predicate "should be a
> predicate function such as `yes-or-no-p'. That is confusing and not
> very meaningful.  What does it mean to be a predicate "such as
> `yes-or-no-p'?

I think examples like that can be helpful, especially with variables
like `confirm-kill-emacs' that non-experienced Emacs users happen upon.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Drew Adams]

> > Also, the doc should not just say that the predicate "should be a
> > predicate function such as `yes-or-no-p'. That is confusing and
> > not very meaningful.  What does it mean to be a predicate "such as
> > `yes-or-no-p'?
> 
> I think examples like that can be helpful, especially with variables
> like `confirm-kill-emacs' that non-experienced Emacs users happen
> upon.

I think what you are suggesting is to correct the language to
say

"If non-nil the value should be a predicate, for example
`yes-or-no-p'."

That would be fine.  The point is that the current language says
that it not only should be a predicate, but a predicate of a
certain kind, namely in some unspecified way similar to
`yes-or-no-p'.  But that is not the case.  The predicate can
check the phase of the moon if you want.

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> I think what you are suggesting is to correct the language to
> say
>
> "If non-nil the value should be a predicate, for example
> `yes-or-no-p'."

Yeah, that's better.  Fixed on trunk.
-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

bug#15455: 24.3.50; wrong defcustom :type for `confirm-kill-emacs'

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> The Value Menu in Customize wrongly give the user no way to specify an
> arbitrary predicate, and wrongly gives the impression that the option
> value must be one of the two predicates presented (or nil).
>
> The :type spec should provide a third possibility for the menu: an
> arbitrary function (which is used as a predicate).

Fixed on trunk.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/