Update step_1.rkt : adding more comments and clarifying the tests

step_1.rkt

 #lang r5rs
+; Authors : Nicolas Verbois - 1366 1600
+;           Nicolas Rosar   - 1443 1900
+;           Group F
+
+; In this step, we've evolved the code to handle messages taking additional parameters.
+; The messages 'setx and 'add are the two of those new types of messages that we implemented.
+; The dispatcher function inside the point object has been renamed "self", as it is more fitting.
+; The self now handles the 'setx and 'add messages, and will return the corresponding function when called.
+; These functions are also defined in the object, but separately before the self function.
 
 (define (point x y)
+  ; The setx function will simply use "set!" to change the value of x to that of the parameter
   (define (setx value)
     (set! x value))
+  ; The add function will perform an addition, for each coordinate, of the current point coordinate (x or y)
+  ; and the parameter point corresponding coordinate ((p 'getx) or (p 'gety)).
   (define (add p)
     (point (+ x (p 'getx)) (+ y (p 'gety))))
   (define (self m)
@@ -10,26 +22,57 @@
           ((eq? m 'gety) y)
           ((eq? m 'type) 'point)
           ((eq? m 'info) (list (self 'type) (self 'getx) (self 'gety)) )
-          ((eq? m 'setx!) setx )
-          ((eq? m 'add) add)
-          (else (display "Message not understood")))) ; error ? 
+          ((eq? m 'setx!) setx) ; the new setx message
+          ((eq? m 'add) add)    ; the new add message
+          (else (display "Message not understood"))))
   self)
 
-(display "coucou")
+
+; Sample code illustrating the execution of the step
+
+; We start by creating two points, p1 and p2
 
 (define p1 (point 1 2))
 (define p2 (point 3 4))
-(display (p1 'getx))
+
+(display (p1 'getx)) ; should display : 1
+(newline)
+
+(display (p1 'gety)) ; should display : 2
+(newline)
+
+(display (p1 'type)) ; should display : point
+(newline)
+
+(display (p1 'info)) ; should display : (point 1 2)
+(newline)
+
+(display '----------)
+(newline)
+
+(display (p2 'getx)) ; should display : 3
 (newline)
-(display (p1 'gety))
+
+(display (p2 'gety)) ; should display : 4
 (newline)
-(display (p1 'type))
+
+(display (p2 'type)) ; should display : point
 (newline)
-(display (p1 'info))
+
+(display (p2 'info)) ; should display : (point 3 4)
 (newline)
+
+(display '----------)
+(newline)
+
+; We change the value of the "x" coordinate of point p1 from 1 to 5
 ((p1 'setx!) 5)
-(display (p1 'getx))
+(display (p1 'getx)) ; should display : 5
 (newline)
-(display ((p1 'add) p2))
+
+; We define a new point p3, which is the result of adding p1 and p2
+(define p3 ((p1 'add) p2))
+(display (p3 'info)) ; should display : (point 8 6)
 (newline)
-(display (p1 'foo))
+
+(display (p1 'foo))  ; should display : Message not understood