Brett Cannon added the comment:
So the exception is explicitly deleted when the `except` block is exited to
prevent leaking memory from the traceback attached to the exception. Hence
there's an implicit `del e` at the end of the `except` block which is what
you're running up against.
But I'm closing this as 'wont fix' because making this edge case work would be
real troublesome and destroy performance whenever you bound the caught
exception. Basically you would have to do the equivalent of:
e = 42
try:
1/0
except ZeroDivisionError as _hidden_e:
_overridden = False
try:
_old_e = e
_overridden = True
except NameError:
pass
e = _hidden_e
# `except` block ...
del e, _hidden_e
if _hidden_flag:
e = _old_e
That's a lot of code to run on every `except` clause that just happens to
shadow a previously existing variable name. Because we try and not make
exceptions too expensive in order to make them usable for occasional control
flow, I don't think we can afford to add all of this for this edge case.
----------
nosy: +brett.cannon
resolution: -> wont fix
stage: -> resolved
status: open -> closed
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<http://bugs.python.org/issue26174>
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