r10884: not verified to be working

diff --git a/fov.lisp b/fov.lisp
index 80c8f5bc105e1cb5faec4de7bd0eb4455e555905..64bbe80c737aaa71ffce0b2618ec9c7bfae71ae5 100644 (file)
--- a/fov.lisp
+++ b/fov.lisp
@@ -208,28 +208,54 @@ Returns: focal-length object-distance image-distance magnification bellows-facto
   "Returns the bellows factor, the ratio of effective aperature to actual aperture."
   (1+ (magnification :focal-length focal-length :object-distance object-distance)))
 
-(defun extension-tube (focal-length &key original-object-distance original-image-distance original-magnification
-                      new-object-distance new-image-distance new-magnification extension-length (units :feet))
+(defun n-args-not-nil (n &rest args)
+  "Returns T when count N of input args are not nil."
+  (= n (count-if-not #'null args)))
+
+(defun extension-tube (focal-length &key original-object-distance 
+                      original-image-distance original-magnification
+                      new-object-distance new-image-distance
+                      new-magnification extension-length (units :feet))
   "Computes the parameters for using extension tubes.
 Requires: 1. original-object-distance, original-image-distance, or original-magnification
           2. new-object-distance, new-image-distance, new-magnification, or extension-length
 Returns: original-object-distance, original-image-distance, original-magnification, original-bellows-factor
          new-object-distance, new-image-distance, new-magnification, extension-length."
   
-  (multiple-value-bind (focal-length o-od o-id o-m o-bf)
+  (when (or (not focal-length) (not units)
+           (not (n-args-not-nil 1 original-object-distance 
+                                original-image-distance
+                                original-magnification))
+           (not (n-args-not-nil 1 new-object-distance 
+                                new-image-distance
+                                new-magnification
+                                extension-length)))
+    (error "Invalid arguments.
+Must set 1 of the following original-object-distance, original-image-distance,
+or original-magnification parameters as well as one of the following parameters
+new-object-distance, new-image-distance, new-magnification, or extension-length."))
+
+  (flet ((ret (ood oid om obf nod nid nm nbf e)
+          (list :focal-length focal-length :original-object-distance ood
+                :original-image-distance oid :original-magnification om
+                :original-bellows-factor obf :new-object-distance nod
+                :new-image-distance nid :new-magnification nm
+                :new-bellows-factor nbf :extension-length e)))
+
+  (multiple-value-bind (focal-length-original o-od o-id o-m o-bf)
       (close-up :focal-length focal-length :object-distance original-object-distance
                :image-distance original-image-distance :magnification original-magnification :units units)
+    (declare (ignore focal-length-original))
     
     (cond
      (extension-length
-      (multiple-value-bind (focal-length n-od n-id n-m n-bf)
+      (multiple-value-bind (focal-length-new n-od n-id n-m n-bf)
          (close-up :focal-length focal-length :image-distance (+ o-id extension-length) :units units)
-       (values o-od o-id o-m o-bf n-od n-id n-m n-bf extension-length)))
+       (declare (ignore focal-length-new))
+       (ret o-od o-id o-m o-bf n-od n-id n-m n-bf extension-length)))
      ((not extension-length)
-      (multiple-value-bind (focal-length n-od n-id n-m n-bf)
+      (multiple-value-bind (focal-length-new n-od n-id n-m n-bf)
          (close-up :focal-length focal-length :object-distance new-object-distance
                    :image-distance new-image-distance :magnification new-magnification :units units)
-       (values o-od o-id o-m o-bf n-od n-id n-m n-bf (- n-id o-id)))))))
-
-
-
+       (declare (ignore focal-length-new))
+       (ret o-od o-id o-m o-bf n-od n-id n-m n-bf (- n-id o-id))))))))