weird-throw-stack.py

import sys

def dump_stack(where):
    print("-- {} --".format(where))
    frame = sys._getframe(1)
    while frame:
        print(frame.f_code.co_name)
        frame = frame.f_back

def f():
    dump_stack("f before yielding")
    yield from g()
    dump_stack("f after yielding")

def g():
    dump_stack("g before yielding")
    yield from h()
    dump_stack("g after yielding")

def h():
    dump_stack("h before yielding")
    try:
        yield
    except Exception:
        pass
    dump_stack("h after yielding")

gen = f()
gen.send(None)
try:
    # Replace this with gen.send(None) and you get sensible stacks
    gen.throw(RuntimeError)
except StopIteration:
    pass