A mechanism for providing automatic interoperation between native objects created in a single language computing environment and objects created in external virtual machines and foreign class systems is discussed. Embodiments of the present invention provides a class definition syntax for objects created in the single language computing environment that provides the ability to directly subclass external classes and implement external interfaces. One embodiment of the present invention also permits a foreign object system to instantiate native objects and to create foreign subclasses of native classes. More specifically, one embodiment of the present invention provides bidirectional mapping between metadata associated with objects created with each of a plurality of different types of foreign object systems and metadata created in a form supported by the single language computing environment.