[no subject]

[CWH at MIT-AI (Carl W. Hoffman)]

We need a form for binding the filename defaults over a given scope.
For instance, if USER-FUNCTION is a function which may be typed from
toplevel and should default filename components, then it should be written
as:

(DEFUN USER-FUNCTION (FILE-NAME ...)
       ...
       (BIND-FILE-NAME-DEFAULTS
	  ;; In here are calls to functions which may change
	  ;; the file name defaults, such as LOAD.
	  (LOAD SOME-OTHER-NEEDED-FILE))
       ;; Here we want to default from the thing the user typed
       ;; previously, not from the call to LOAD.
       (MAKE-USE-OF (FILE-EXPAND-PATHNAME FILE-NAME)))

Likewise, calls to USER-FUNCTION from within other code would be enclosed
in a BIND-FILE-NAME-DEFAULTS.  Using this form is preferable to explicitly
binding FILE-DEFAULT-FN1, etc. since it is file system independent.