langs a-z

Task/Add-a-variable-to-a-class-instance-at-runtime/Oz/add-a-variable-to-a-class-instance-at-runtime.oz

@@ -0,0 +1,29 @@
+declare
+  %% Creates a new class derived from BaseClass
+  %% with an added feature (==public immutable attribute)
+  fun {AddFeature BaseClass FeatureName FeatureValue}
+     class DerivedClass from BaseClass
+        feat
+	   %% "FeatureName" is escaped, otherwise a new variable
+	   %% refering to a private feature would be created
+           !FeatureName:FeatureValue
+     end
+  in
+     DerivedClass
+  end
+
+  class Base
+     feat
+        bar:1
+
+     meth init
+        skip
+     end
+  end
+
+  Derived = {AddFeature Base foo 2}
+
+  Instance = {New Derived init}
+in
+  {Show Instance.bar} %% inherited feature
+  {Show Instance.foo} %% feature of "synthesized" class