CDE

Task/Exceptions/Common-Lisp/exceptions.lisp

@@ -0,0 +1,14 @@
+(define-condition unexpected-odd-number (error)
+  ((number :reader number :initarg :number))
+  (:report (lambda (condition stream)
+             (format stream "Unexpected odd number: ~w."
+                     (number condition)))))
+
+(defun get-number (&aux (n (random 100)))
+  (if (not (oddp n)) n
+    (error 'unexpected-odd-number :number n)))
+
+(defun get-even-number ()
+  (handler-case (get-number)
+    (unexpected-odd-number (condition)
+      (1+ (number condition)))))