How to throw a value when exiting recursive edit (without using setq) - emacs

Question

Is it possible to throw a value when exiting recursive edit without using setq?
The functions below work correctly with setq, however, my goal is to eliminate unnecessary global variables (if possible) -- especially file names -- and use let bound variables instead. In the context of throwing a value when exiting recursive edit, however, I have been unable to devise a method that does not use a global variable for the file name.
In this example, I am using lawlist-save-as in conjunction with dired-read-file-name to enter dired-mode and select a file name or a path. Pressing the enter key on a file name selects a file. Pressing the enter key on a directory name or the two (2) dots moves up one directory. Pressing the enter key on the line with just one (1) dot, means select only the path in the current directory. The value of the file name or path is passed back to the function lawlist-save-as through the last line of dired-read-file-name.
[Although not necessary for this example (but just in case anyone is curious), getting marked files with (dired-get-marked-files) is used for a different situation, such as attaching multiple files to an e-mail using Wanderlust -- in which case, I use the condition ((listp lawlist-filename) (throw 'exit nil)). And, of course, opening a file is self-explanatory -- used for a situation when dired-mode is entered regularly and then just pressing the return key on a file to be opened.]
(require 'dired)
(defvar lawlist-filename nil)
(defvar save-as-buffer-filename nil)
(defvar save-as-variable nil)
(defvar dired-buffer-name nil)
(defun dired-read-file-name (&optional directory)
(let ((working-buffer (buffer-name)))
(if directory
(dired directory)
(dired nil))
(let ((dired-buffer-name (buffer-name)))
(if save-as-buffer-filename
(progn
(goto-char (point-min))
(re-search-forward (file-name-nondirectory save-as-buffer-filename) nil t)))
(recursive-edit)
(kill-buffer dired-buffer-name)
(switch-to-buffer working-buffer)
lawlist-filename)))
;; select file or directory.
(define-key dired-mode-map (kbd "<return>") (lambda () (interactive)
(setq lawlist-filename
(if (or (re-search-backward "^*" nil t)
(re-search-forward "^*" nil t))
(dired-get-marked-files)
(dired-get-file-for-visit)))
(cond
((listp lawlist-filename)
(throw 'exit nil))
;; open file
((and (not (file-directory-p lawlist-filename))
(file-exists-p lawlist-filename)
(not (equal lawlist-filename (concat (file-name-directory lawlist-filename) ".")))
(not save-as-variable))
(find-file lawlist-filename))
;; save-as
((and (not (file-directory-p lawlist-filename))
(file-exists-p lawlist-filename)
(not (equal lawlist-filename (concat (file-name-directory lawlist-filename) "."))))
(throw 'exit nil))
;; go up one directory
((and (file-directory-p lawlist-filename)
(not (equal lawlist-filename (concat (file-name-directory lawlist-filename) "."))))
(setq dired-buffer-name (buffer-name))
(dired-find-file)
(goto-char (point-min))
(re-search-forward " \\.\\.$" nil t)
(kill-buffer dired-buffer-name)
(setq dired-buffer-name (buffer-name)))
;; only use current path for save-as situation.
((and (equal lawlist-filename (concat (file-name-directory lawlist-filename) "."))
save-as-variable)
(setq lawlist-filename (expand-file-name default-directory))
(throw 'exit nil)) )))
(defun lawlist-save-as ()
(interactive)
(setq save-as-variable t)
(if (buffer-file-name)
(setq save-as-buffer-filename (buffer-file-name)))
(let ((proposed-filename (dired-read-file-name)))
(when proposed-filename ;; needed if aborting recursive-edit
(setq save-as-variable nil)
(let ((save-as-filename (read-string "Save-As: "
(concat proposed-filename (when (file-directory-p proposed-filename) (buffer-name))))))
(setq save-as-buffer-filename nil)
(when (and save-as-filename (file-exists-p save-as-filename))
(or (y-or-n-p (format "File `%s' exists; overwrite? " save-as-filename))
(error "Canceled")))
(set-visited-file-name save-as-filename)
(set-buffer-modified-p t)
(and (buffer-file-name)
(file-writable-p buffer-file-name)
(setq buffer-read-only nil))
(save-buffer)))))

Answer 1

recursive-edit is just a function that runs a command loop. All stuff that is valid for lisp applies.
So if you encapsulate recursive-edit into a let which locally binds some variable, say test, and if you setq this variable during the recursive edit session this variable is just set locally in the scope of the let.
Example:
Run the following with C-x C-e:
(let (test)
(recursive-edit)
(message "test=%S" test))
You will be in the command loop of the recursive edit. Then set test via M-: (setq test "That is my test.").
Afterwards press M-C-c to exit the recursive edit session.
The message test=\"That is my test.\" is be printed out but the symbol test is still unbound.