[Audacity-nyquist] Q: unwind_protect

[Steven J. <jo...@sw...>]

I'm trying to write an error handler in XLISP and am confused about
unwind-protect. 

Its my understanding from reading the manual that the "clean up" code is
executed unconditionally.  Calling (foo nil) executes both the protected
and clean-up forms. Calling (foo t) generates an error as expected but
the clean up code is not executed.  What am I missing?

 

(defun foo (flag)
  (unwind-protect
      (progn
	(if flag
	    (error ""))
	(format t "protected expression ~%"))
    (progn
      (format t "clean-up expression ~%"))))




Thanks
Steven Jones