Re: declare function/macro private

[Stefan Monnier]

> The point was just to support Paul Rankin's position that a '--'
> substring isn't a reliable determinant of a function's public/private
> nature, so can't be used as an alternative to an explicit (optional)
> declaration.

FWIW, I do not think a function should be considered non-internal just
because it has to be declared as interactive.

Similarly, the default value of a `foo-function` or `foo-hook` variable
can very much be an internal function, IMO.

The point of "internal" is that other code shouldn't use this directly
because it is subject to change, removal, or unexpected behavior if
called in a different context, ...

More concretely it means that end users are recommended not to do:

   (define-key company-active-map [my-key-sequence]
     #'company--select-next-and-warn)

If they want to use another key than `M-n` they should presumably do:

   (define-key company-active-map [my-key-sequence]
     (lookup-key company-active-map (kbd "M-n")))

[ I don't know if this use of "--" in company.el was a good idea,
  OTOH. ;-)  ]


        Stefan