[cells-cvs] CVS cells/tutorial

[ktilton]

Update of /project/cells/cvsroot/cells/tutorial
In directory clnet:/tmp/cvs-serv2216/tutorial

Modified Files:
	01c-cascade.lisp 
Log Message:
evolving geometry; refinement of test case 01c-cascade

--- /project/cells/cvsroot/cells/tutorial/01c-cascade.lisp	2006/05/30 02:47:45	1.1
+++ /project/cells/cvsroot/cells/tutorial/01c-cascade.lisp	2006/06/05 00:01:22	1.2
@@ -1,31 +1,94 @@
-#| Now we have automatic state management (including change propagation)
+#| 
+
+Now we have automatic state management (including change propagation)
 outside the Cells model as well as in. Now lets look at cascading change
 by adding another level of computation, so A->B->C.
 
-[Actually, I see I need to make this a little deeper, since area has
-a direct dependency on width. Not tonight. :)]
+In this case: len->area->brightness
+Also: len->width->area->brightness
+
+That leads to some complications I will discuss, but no assertions here
+enforce correct behavior in re those complications. Soon. :)
 
 |#
 
 (defpackage #:tu-depth (:use :cl :cells))
 (in-package #:tu-depth)
 
+(defmacro start-finish (key rule)
+  `(progn
+     (print (list :start ,key))
+     (prog1
+         (progn ,rule)
+       (print (list :finish ,key)))))
 
 (defmodel rectangle ()
-  ((area :initarg :area :accessor area
-     :initform (c? (print :compue-area)
-                 (* (len self)(width self))))
+  ((lumens :initform 1000000 :reader lumens)
    (len :initarg :len :accessor len
-     :initform (c? (print :compute-len)
-                 (* 2 (width self))))
+     :initform (c? (start-finish :len
+                     (* 2 (width self)))))
+   (area :initarg :area :accessor area
+     :initform (c? (start-finish :area
+                     (* (len self)(width self)))))
    (width :initarg :width :accessor width
-     :initform (c? (print :compute-width)
-                 (floor (len self) 2)))))
+     :initform (c? (start-finish :width
+                     (floor (len self) 2))))
+   (brightness :reader brightness
+     :initform (c? (start-finish :brightness
+                     (/ (^lumens) (^area)))))
+   ))
 
 #+test
-(let ((r (make-instance 'rectangle :len (c-in 42))))
-  (cells::ct-assert (eql 21 (width r)))
-  (cells::ct-assert (eql (* 21 42) (area r)))
+(let ((r (make-instance 'rectangle :len (c-in 100))))
+  (cells::ct-assert (eql 50 (width r)))
+  (cells::ct-assert (eql 5000 (area r)))
+  (cells::ct-assert (eql 200 (brightness r)))
   (cells::ct-assert (= 1000 (setf (len r) 1000)))
-  (cells::ct-assert (eql 500000 (area r))))
+  (cells::ct-assert (eql 500000 (area r)))
+  (cells::ct-assert (eql 2 (brightness r))))
+
+#| --- discussion ----------------------------
+
+The output in Cells is:
+
+(:START :AREA) 
+(:START :WIDTH) 
+(:finish :WIDTH) 
+(:finish :AREA) 
+(:START :BRIGHTNESS) 
+(:finish :BRIGHTNESS) 
+(CELTK::ATTEMPTING (EQL 50 (WIDTH R))) 
+(CELTK::ATTEMPTING (EQL 5000 (AREA R))) 
+(CELTK::ATTEMPTING (EQL 200 (BRIGHTNESS R))) 
+(CELTK::ATTEMPTING (= 1000 (SETF (LEN R) 1000))) 
+0> c-propagate-to-users > notifying users of | [i :=[24]LEN/#<RECTANGLE>] | (AREA WIDTH)
+
+Notice here that the LEN cell is about to tell both the width and area to recalculate,
+since area depends (of course) on len and (rather artificially) width also derives
+from LEN.
+
+ie, This example has accidentally deviated into more complexity than intended. But we are 
+approaching these issues anyay, so I will leave it for now. We can always break it up
+later.
+
+Let's continue:
+
+(:START :WIDTH) 
+(:finish :WIDTH) 
+(:START :AREA) 
+(:finish :AREA) 
+
+Fine, now here comes the challenge. Width is also going to tell area to recalculate:
+
+0> c-propagate-to-users > notifying users of | [? :<vld>=[24]WIDTH/#<RECTANGLE>] | (AREA)
+0> c-propagate-to-users > notifying users of | [? :<vld>=[24]AREA/#<RECTANGLE>] | (BRIGHTNESS)
+
+Correct: Area does not actually run its rule since it already did so when notified by LEN,
+ but it does propagate to brightness.
+
+(:START :BRIGHTNESS) 
+(:finish :BRIGHTNESS)  
+(CELTK::ATTEMPTING (EQL 500000 (AREA R))) 
+(CELTK::ATTEMPTING (EQL 2 (BRIGHTNESS R))) 
 
+|#
\ No newline at end of file