Close #14963: Use an iterative algorithm in contextlib.ExitStack.__exit__ (Patch by Alon Horev)
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index ead1155..f5232b6 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -225,32 +225,21 @@
return self
def __exit__(self, *exc_details):
- if not self._exit_callbacks:
- return
- # This looks complicated, but it is really just
- # setting up a chain of try-expect statements to ensure
- # that outer callbacks still get invoked even if an
- # inner one throws an exception
- def _invoke_next_callback(exc_details):
- # Callbacks are removed from the list in FIFO order
- # but the recursion means they're invoked in LIFO order
- cb = self._exit_callbacks.popleft()
- if not self._exit_callbacks:
- # Innermost callback is invoked directly
- return cb(*exc_details)
- # More callbacks left, so descend another level in the stack
+ # Callbacks are invoked in LIFO order to match the behaviour of
+ # nested context managers
+ suppressed_exc = False
+ while self._exit_callbacks:
+ cb = self._exit_callbacks.pop()
try:
- suppress_exc = _invoke_next_callback(exc_details)
- except:
- suppress_exc = cb(*sys.exc_info())
- # Check if this cb suppressed the inner exception
- if not suppress_exc:
- raise
- else:
- # Check if inner cb suppressed the original exception
- if suppress_exc:
+ if cb(*exc_details):
+ suppressed_exc = True
exc_details = (None, None, None)
- suppress_exc = cb(*exc_details) or suppress_exc
- return suppress_exc
- # Kick off the recursive chain
- return _invoke_next_callback(exc_details)
+ except:
+ new_exc_details = sys.exc_info()
+ if exc_details != (None, None, None):
+ # simulate the stack of exceptions by setting the context
+ new_exc_details[1].__context__ = exc_details[1]
+ if not self._exit_callbacks:
+ raise
+ exc_details = new_exc_details
+ return suppressed_exc