You can run a profiler to determine which functions actually get called. I'm reminded of a Smalltalk hack called Spoon. It required two systems: a host system

You can run a profiler to determine which functions actually get called. I'm reminded of a Smalltalk hack called Spoon. It required two systems: a host system running the full Smalltalk with all its classes, and a target system which had the barest possible Smalltalk environment. Any time an attempt was made to access a class that didn't exist on the target system, it would ask the host system for that class and if available, download it in serialized bytecode form and run it. This may have worked at method level granularity -- i.e., classes were only populated with methods that were actually used on the target system -- I'm not sure. But the result was the target system only contained enough of Smalltalk to actually run the program.