Close #19092: ExitStack now reraises exceptions from __exit__
Report and patch by Hrvoje Nikšić
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 0b6bf71..f8e026b 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -225,6 +225,8 @@
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]
@@ -239,17 +241,27 @@
# 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 e52ed91..9e45f70 100644
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -573,6 +573,43 @@
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)
diff --git a/Misc/ACKS b/Misc/ACKS
index 63c126c..400f528 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -882,7 +882,7 @@
Jonathan Niehof
Gustavo Niemeyer
Oscar Nierstrasz
-Hrvoje Niksic
+Hrvoje Nikšić
Gregory Nofi
Jesse Noller
Bill Noon
diff --git a/Misc/NEWS b/Misc/NEWS
index 7898b9b..30e6111 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -71,6 +71,10 @@
Library
-------
+- Issue #19092: contextlib.ExitStack now correctly reraises exceptions
+ from the __exit__ callbacks of inner context managers (Patch by Hrvoje
+ Nikšić)
+
- Issue #12641: Avoid passing "-mno-cygwin" to the mingw32 compiler, except
when necessary. Patch by Oscar Benjamin.