CDE

Task/Constrained-genericity/PicoLisp/constrained-genericity.l

@@ -0,0 +1,18 @@
+(class +Eatable)
+
+(dm eat> ()
+   (prinl "I'm eatable") )
+
+
+(class +FoodBox)
+# obj
+
+(dm set> (Obj)
+   (unless (method 'eat> Obj)                # Check if the object is eatable
+      (quit "Object is not eatable" Obj) )
+   (=: obj Obj) )                            # If so, set the object
+
+
+(let (Box (new '(+FoodBox))  Eat (new '(+Eatable))  NoEat (new '(+Bla)))
+   (set> Box Eat)       # Works
+   (set> Box NoEat) )   # Gives an error