How to check if class is exception class?

Question

I define a custom exception:

>>> class MyException(Exception):
>>>     pass

I create an exception instance:

>>> a = MyException()

I check if this is an exception. As expected, it is:

>>> isinstance(a, Exception)
True

But how do I check if the class is an exception class?

>>> myclass = MyException
>>> isinstance(myclass, Exception)
False

Chetan Ameta · Accepted Answer · 2019-01-28 10:14:15Z

8

you can check if one class is inherited from other class by using issubclass function

print issubclass(MyException, Exception)

result:

True

answered Jan 28, 2019 at 10:14

Chetan Ameta

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1 Comment

volingas Over a year ago

Cool. I need it to distinguish between object instances and sub-classes of Exception (for unit testing), and unfortunately issubclass fails for non-class objects.

fixatd · Accepted Answer · 2019-01-28 10:21:30Z

0

You can try checking if Exception is under __bases__:

>>> my_class = MyException
>>> Exception in my_class.__bases__
True

answered Jan 28, 2019 at 10:21

fixatd

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1 Comment

volingas Over a year ago

Thanks, a bit hacky

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