interate over the a public interface?

[thi <ttn@mingle.glug.org>]

Clark McGrew writes:

 > I've got an interactive environment that I'd like to include lots of
 > small modules into.  In otherwords, I'd like to have a module boot
 > 
 > (define-module (boot)
 > 	       :use-module (mod1)
 > 	       :use-module (mod2)
 > 	       :use-module (mod3))
 > 
 > that I can include by saying
 > 
 > (use-module (boot))
 > 
 > and get the exports of mod1, mod2, &c.  
 > 
 > I've had some success with module-for-each, but it interates over all
 > variables in a module (local and exported).  Is there a way to only
 > iterate over the public interface?

this is called in my mind the re-export problem.  there might be a
canonical name or solution these days (or soon) but for now you can do
something like this:

;; Re-export variables from module named OTHER-MODULE-NAME.  If SPECIFICALLY
;; is the empty list, all public variables from OTHER-MODULE-NAME are
;; exported, otherwise, each element in SPECIFICALLY is taken to be either a
;; symbol naming a variable to be exported, or a pair of symbols of the form
;; (OLD-NAME . NEW-NAME) describing the mapping to be used.  OLD-NAME should
;; name an exported variable in OTHER-MODULE-NAME.
;;
(defmacro reexport-from-module (other-module-name . specifically)
  `(let ((cur-mod   (current-module))
	 (other-mod (resolve-module ',other-module-name))
	 (spec      (map (lambda (x) (if (pair? x) x (cons x x))) ; for assq
			 ',specifically)))
     (let ((add! (lambda (old-name new-name)
		   (module-add! (module-public-interface cur-mod)
				new-name
				(module-variable other-mod old-name)))))
       (module-map (lambda (sym x)
		     (if (eq? '() spec)
			 (add! sym sym)
			 (let ((try (assq sym spec)))
			   (and try (add! (car try) (cdr try))))))
		   (module-public-interface other-mod)))))

note that this also handles renaming, which can be useful when the
constituent modules export different procedures or variables but w/ the
same name.  such is the job of the shady import/export specialist that
is your top-level module: to launder all bindings into oblivion (insert
international-bank-account-smiley here B-).  aren't you glad you're
using guile?

thi,
memorizing 93-digit numbers to the sounds of shredding paper...