Re: very mysterious behaviour from rmail-output-to-rmail-file

[Kevin Rodgers]

Florian von Savigny wrote:
> I'm trying to debug a function I have written which is meant to be
> called in rmail buffers and basically should sort a message
> somewhere. The directory of that somewhere should be returned by
> another function which works well on its own:
>
> (defun rmail-output-to-afile ()
>   (interactive)
>   (rmail-output-to-rmail-file (concat
>                           (nth 1 (current-contract))
>                           "/putmail")))
...
> But if the function definition is left as above, it will only go as
> far as asking whether it should create the file (if it isn't already
> there). Then, it will emit the error "Wrong type argument: stringp,
> nil", and stop.
>
> The backtrace says:
>
> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
> 
rmail-output-to-rmail-file("/home/uebersetzer/auftraege/20040203.hau45147ess/putmail")
>   rmail-output-to-afile()
> * call-interactively(rmail-output-to-afile)
>   execute-extended-command(nil)
>   call-interactively(execute-extended-command)
>
>
> This is either a no-brainer, or a deep mystery. To me, it's the
> latter. Can anybody help me?

,----[ C-h f rmail-output-to-rmail-file RET ]
| rmail-output-to-rmail-file is an interactive autoloaded Lisp function 
in `rmailout'.
| [Arg list not available until function definition is loaded.]
|
| Append the current message to an Rmail file named FILE-NAME.
| If the file does not exist, ask if it should be created.
| If file is being visited, the message is appended to the Emacs
| buffer visiting that file.
| If the file exists and is not an Rmail file, the message is
| appended in inbox format, the same way `rmail-output' does it.
|
| The default file name comes from `rmail-default-rmail-file',
| which is updated to the name you use in this command.

Hmmm, perhaps that variable isn't set...

| A prefix argument N says to output N consecutive messages
| starting with the current one.  Deleted messages are skipped and don't 
count.
|
| If optional argument STAY is non-nil, then leave the last filed
| mesasge up instead of moving forward to the next non-deleted message.
`----

Then if you look at the source for rmail-output-to-rmail-file, it's
preceded by this comment:

;;; There are functions elsewhere in Emacs that use this function;
;;; look at them before you change the calling method.

I would try binding that variable, which is set by all the Emacs
commands that call rmail-output-to-rmail-file (via
rmail-output-read-rmail-file-name, C-h v):

(defun rmail-output-to-afile ()
  "Append the current message to the \"putfile\" Rmail file
in the `current-contract' directory.
See `rmail-output-to-file'."
  (interactive)
  (let ((rmail-default-rmail-file
         (expand-file-name "putmail" (nth 1 (current-contract)))))
    (rmail-output-to-rmail-file rmail-default-rmail-file)))

--
Kevin Rodgers