Eclipse is able to utilize compiled bytecode to enable "magic refactor" functionality--renaming methods, tracing up and down class hierarchies and tracing through method calls.
What technical barriers exist that make this harder to do for languages like Python and Javascript?
so it turns out that tracing of static information like methods and class hierarchies is perfectly possible in python. PyDev eclipse plugin does it. PyLint plugin attempts to do static analysis even on stuff like dynamic variables by assuming that nothing funky happens at runtime and does a pretty good job.