diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/contextlib.py | 18 | ||||
| -rw-r--r-- | Lib/test/test_contextlib.py | 37 |
2 files changed, 52 insertions, 3 deletions
diff --git a/Lib/contextlib.py b/Lib/contextlib.py index 3222ac8..aaab095 100644 --- a/Lib/contextlib.py +++ b/Lib/contextlib.py @@ -237,6 +237,8 @@ class ExitStack(object): return self def __exit__(self, *exc_details): + received_exc = exc_details[0] is not None + # We manipulate the exception state so it behaves as though # we were actually nesting multiple with statements frame_exc = sys.exc_info()[1] @@ -251,17 +253,27 @@ class ExitStack(object): # Callbacks are invoked in LIFO order to match the behaviour of # nested context managers suppressed_exc = False + pending_raise = False while self._exit_callbacks: cb = self._exit_callbacks.pop() try: if cb(*exc_details): suppressed_exc = True + pending_raise = False exc_details = (None, None, None) except: new_exc_details = sys.exc_info() # simulate the stack of exceptions by setting the context _fix_exception_context(new_exc_details[1], exc_details[1]) - if not self._exit_callbacks: - raise + pending_raise = True exc_details = new_exc_details - return suppressed_exc + if pending_raise: + try: + # bare "raise exc_details[1]" replaces our carefully + # set-up context + fixed_ctx = exc_details[1].__context__ + raise exc_details[1] + except BaseException: + exc_details[1].__context__ = fixed_ctx + raise + return received_exc and suppressed_exc diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py index a38cc48..2892917 100644 --- a/Lib/test/test_contextlib.py +++ b/Lib/test/test_contextlib.py @@ -573,6 +573,43 @@ class TestExitStack(unittest.TestCase): self.assertIsInstance(inner_exc, ValueError) self.assertIsInstance(inner_exc.__context__, ZeroDivisionError) + def test_exit_exception_non_suppressing(self): + # http://bugs.python.org/issue19092 + def raise_exc(exc): + raise exc + + def suppress_exc(*exc_details): + return True + + try: + with ExitStack() as stack: + stack.callback(lambda: None) + stack.callback(raise_exc, IndexError) + except Exception as exc: + self.assertIsInstance(exc, IndexError) + else: + self.fail("Expected IndexError, but no exception was raised") + + try: + with ExitStack() as stack: + stack.callback(raise_exc, KeyError) + stack.push(suppress_exc) + stack.callback(raise_exc, IndexError) + except Exception as exc: + self.assertIsInstance(exc, KeyError) + else: + self.fail("Expected KeyError, but no exception was raised") + + def test_body_exception_suppress(self): + def suppress_exc(*exc_details): + return True + try: + with ExitStack() as stack: + stack.push(suppress_exc) + 1/0 + except IndexError as exc: + self.fail("Expected no exception, got IndexError") + def test_exit_exception_chaining_suppress(self): with ExitStack() as stack: stack.push(lambda *exc: True) |