Re: What's wrong with this elisp code?

[Glenn Morris <rgm+news@stanford.edu>]

ken wrote:

> Is there some other way that this variable could be defined other than
> with defvar?

Yes, the way that Jeff Miller already said: inside a let binding so
that it only exists for the duration of the calling function:

bar -> Symbol's value as variable is void: bar

(defun foo ()
  (let ((bar "BAR"))
    (message "the value of bar is %s" bar)))

(foo) -> "the value of bar is BAR"

bar -> Symbol's value as variable is void: bar


Making your own definition of the variable `bar' outside of the
function `foo' will be no help at all, since this global binding is
hidden inside the let statement.

The Emacs calendar does a few things in this way, which can make it
difficult to follow.

To achieve what you want, use the already posted solution, or adapt
the definition of the function `diary-mail-entries' (see documentation
of that function for example cron usage), eg to:

(require 'diary-lib)
(defun diary-to-file (file &optional ndays)
  "Write the diary entries for the next NDAYS (default 1) to FILE."
  (interactive (list (read-file-name "Write diary to file: ")
                     (prefix-numeric-value current-prefix-arg)))
  (let ((diary-display-hook 'fancy-diary-display))
    (list-diary-entries (calendar-current-date) (or ndays 1))
    (with-temp-buffer
      (insert
       (if (get-buffer fancy-diary-buffer)
           (with-current-buffer fancy-diary-buffer (buffer-string))
         "No diary entries found"))
      (write-region (point-min) (point-max) file nil nil nil t))))