Lokesh Setia  <lsetia@lsetia.hss.hns.com> wrote:
+---------------
| Say, I have to implement a function in C for use with guile which has
| to return values through its parameters.
+---------------

Not a good idea.

+---------------
|    (c-func val1 val2 val3 'result1 'result2)
| The user passes some values in val1, val2, val3, and gets the answers
| in symbols result1 and result2.
| Of course, I could have designed the function such that the user will
| have to say:
| 
| (set! result (c-func val1 val2 val3))
| (set! result1 (car result))
| (set! result2 (cdr result))
+---------------

Dunno 'bout Guile, but C code called from MzScheme can return R5RS
multiple values, so the clean way is:

	(call-with-values
	  (lambda () (c-func val1 val2 val3))
	  (lambda (result1 result2)
	    ...code that uses results 1 & 2...
	    ))

or at the top level:

	(define-values (result1 result2) (c-func val1 val2 val3))

or if you insist on doing a "set!":

	(set!-values (result1 result2) (c-func val1 val2 val3))


-Rob

-----
Rob Warnock, 41L-955		rpw3@sgi.com
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