# HG changeset patch
# User Marcus Pearce <m.pearce@gold.ac.uk>
# Date 1302111023 -3600
# Node ID df2505dc6d1143c46336f2c83cb9873194c68295
# Parent  d5ace22748dfb2ae6478760feb76c1633ffd79ad
handle null time value in converting mtp-event to amuse-event.

diff -r d5ace22748df -r df2505dc6d11 implementations/mtp/methods.lisp
--- a/implementations/mtp/methods.lisp	Thu Mar 24 15:54:27 2011 +0000
+++ b/implementations/mtp/methods.lisp	Wed Apr 06 18:30:23 2011 +0100
@@ -112,12 +112,14 @@
           (setf (slot-value mtp-event (car slts)) (convert-time-slot (car db-atts) timebase))
           (setf (slot-value mtp-event (car slts)) (car db-atts))))))
 
-  (defun convert-time-slot (value timebase)
-    "Convert native representation of time into a representation where
+(defun convert-time-slot (value timebase)
+  "Convert native representation of time into a representation where
     a crotchet has a value of 96."
-    (let ((multiplier (/ 96 timebase)))
-      (* value multiplier)))
-  
+  (if (or (null value) (null timebase))
+      nil
+      (let ((multiplier (/ 96 timebase)))
+        (* value multiplier))))
+
 ;;; Monodies 
 
 (defmethod monody ((identifier mtp-composition-identifier))