Introspect Python Stack Frames

Python is great at introspecting itself. But could a function introspectively know its caller? Answer: Yes, at least for CPython.

inspect.currentframe() will do just that, which simply calls sys._getframe(1). sys._getframe take an optional integer argument i, and returns the i-th stack frame from the top. (So 0-th is yourself, 1-th is your caller, and so on.)

Nevertheless, sys._getframe is a CPython implementation detail, and should not be expected to be supported in all Python implementations. logging module uses sys._getframe for finding caller function’s name, and it has a comment warning you that in IronPython sys._getframe might return None. In that case, logging uses a trick for retrieving a stack frame: It throws an exception and then immediately catches it, and the traceback object will include a stack frame.