Another update from ingydotnet^djgoku

Task/Inheritance-Single/TXR/inheritance-single-3.txr

@@ -0,0 +1,23 @@
+(defstruct animal nil
+  name
+  (:method get-name (me)
+    (if me.name me.name (error `get-name: animal @me has no name`)))
+  (:method speak (me stream)
+    (error "abstract animal cannot speak")))
+
+(defstruct dog animal
+  (:method speak (me : (stream *stdout*))
+    (put-line `@{me.(get-name)}: bark!` stream)))
+
+(defstruct cat animal
+  (:method speak (me : (stream *stdout*))
+    (put-line `@{me.(get-name)}: meow!` stream)))
+
+(defstruct lab dog)
+
+(defstruct collie dog)
+
+(let ((pet1 (new collie name "Lassie"))
+      (pet2 (new cat name "Max")))
+  pet1.(speak)
+  pet2.(speak))