Context Manager getting str instead of AttributeError instance
ian.g.kelly at gmail.com
Thu Mar 15 20:49:02 CET 2012
On Thu, Mar 15, 2012 at 1:10 PM, Prasad, Ramit
<ramit.prasad at jpmorgan.com> wrote:
>> Prasad, Ramit wrote:
>> > So I have a context manager used to catch errors
>> > def __exit__( self, exceptionClass, exception, tracebackObject ):
>> > if isinstance( exception, self.exceptionClasses ):
>> > #do something here
>> > Normally exception would be the exception instance, but for
>> > AttributeError it seems to be a string instead.
>> I don't think so:
>> >>> class A(object):
>> ... def __enter__(self): return self
>> ... def __exit__(self, *args): print args
>> >>> with A() as a:
>> ... a.x
>> (<type 'exceptions.AttributeError'>, AttributeError("'A' object has no
>> attribute 'x'",), <traceback object at 0x7f57b70f22d8>)
>> Traceback (most recent call last):
>> File "<stdin>", line 2, in <module>
>> AttributeError: 'A' object has no attribute 'x'
>> > 1) Why is AttributeError different than the other built-ins
>> > in this respect?
>> > 2) Are there other standard errors like this (I know
>> > that SystemExit is different as well)?
>> > 3) Taking into account that I want to include subclasses of
>> > classes listed in self.exceptionClasses, Is there a better check I can
>> > use?
> Not sure why mine behaves differently:
> Python 2.6.6 (r266:84292, Dec 17 2010, 12:36:53) [MSC v.1500 32 bit (Intel)] on win32
>>>> class A(object):
> ... def __enter__(self): return self
> ... def __exit__(self, *args): print args
>>>> with A() as a:
> ... a.x
> (<type 'exceptions.AttributeError'>, "'A' object has no attribute 'x'", <traceback object at 0x1817F648>)
> AttributeError: 'A' object has no attribute 'x'
> As you can see, I am getting a string while you are not.
Looks like a version difference. I don't have Python 2.6 handy to
test on, but I get a str in Python 2.5 and an AttributeError instance
in Python 2.7.
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