Re: setting non-user variables

[Héctor Lahoz]

Drew Adams wrote:
> > > (make-variable-buffer-local
> > >  (defvar mpkg-master-file nil
> > >          "The path of the video associated to the current buffer"))
> > >
> > > With 23 I could set the variable interactively, with 24 I can't.
> > 
> > I can confirm that (Emacs 26.0.50 here). Variables defined through
> > defvar seem not to be indexed, whether buffer local or not. If you
> > use `defcustom', though, this will work:
> > 
> >   (defcustom mpkg-master-file nil "...")
> 
> Yes, `set-variable' is for "user variables", aka user options,
> only, aka symbols that satisfy predicate `user-variable-p'.
> 
> Today, that means a variable that is defined using defcustom,
> or an alias to such a variable.
> 
> It USED to also mean any variable whose doc string begins with `*'.
> Alas (IMHO), this feature was removed from Emacs 23 (i.e., long ago).
> 
> In Emacs 22 and prior you could do this:
> 
> (defvar foo  42 "*This is foo.")
> (put 'foo 'variable-interactive "nWidth: ")
> 
> M-x set-variable foo RET
> 
>  Width: 13 RET
> 
> And `foo' was available for completion (e.g. `f TAB') using
> `set-variable'.
> 
> Giving a variable a `variable-interactive' property tells
> `set-variable' how to read a value for it.
> 

You hit the nail on the head. In fact there is a "*" at the
beginning of the docstring and I was wondering why I put it
there some years ago.

Thanks a lot.