[Python-Dev] the current behavior of try: ... finally:

[Michele Simionato]

All this talk about try: ... finally: and exceptions reminded me of a curious
behavior I discovered a while back, i.e. that finally can swallow
your exceptions. This is a contrived example, but shows the point:

def divide1(n1, n2): 
    try:
        result = n1/n2
    finally:
        print "cleanup"
        result = "Infinity\n"
        return result # the exception is swallowed away

def divide2(n1, n2):
    try:
        result = n1/n2
    finally:
        print "cleanup"
        result = "Infinity\n"
    return result # the exception is NOT swallowed away

print divide1(10, 0) # no-exception
print divide2(10, 0) # error

If there is an indentation error in "divide2" and the return line is too
indented the exceptions get swallowed by the finally clause.

I am not sure if this is good or bad, but sure it surprised me that a
finally clause could hide my exception.

                     Michele Simionato