Re: Filename of buffer into kill-ring functionality

[Kevin Rodgers]

Reiner Steib wrote:
> On Thu, Aug 31 2006, Kevin Rodgers wrote:
>
> > (defun kill-new-string-variable (variable)
> >   "Make the string value of VARIABLE the latest kill in the kill ring."
> >   (interactive (let ((current-buffer (current-buffer)))
> >                  (intern (completing-read "Variable: " obarray
> >                                           (lambda (symbol)
> >                                             (with-current-buffer current-buffer
> >                                               (and (boundp symbol)
> >                                                    (stringp
> >                                                     (symbol-value symbol)))))
>
> Is there a reason why you use (boundp symbol) inside
> (with-current-buffer ...)?  In other words: Is there any difference
> between these variants?
>
> (with-current-buffer current-buffer
>   (and (boundp symbol)
>        (stringp (symbol-value symbol))))
>
> (and (boundp symbol)
>      (with-current-buffer current-buffer
>        (stringp (symbol-value symbol))))

The reason with-current-buffer is necessary at all is that the predicate
is run by completing-read with the minibuffer as the current buffer.  I
did it the first way when I first realized that, and it was simpler to
just wrap the entire body of the predicate.

Whether there's a difference between the two depends on whether a
variable with a buffer local value can be unbound globally (or in other
buffers, like the minibuffer).  I think that depends on how buffer local
bindings are implemented, and the first way is safer since it doesn't
depend on how that.

--
Kevin