CODEWITHSUNDEEP
python
ari
ari

Reputation: 4523

Python not catching exception

For some reason my code is not catching an exception when I throw it. I have

def trim_rad(rad):
    ...

    if not modrad.shape[0]:
        raise IndexError("Couldn't find main chunk")
    return modrad, thetas

Then later I call that function:

try:
    modrad, thetas = trim_rad(rad)
except IndexError("Couldn't find main chunk"):
    return 0

Yet I still get a traceback with that exception. What am I doing wrong?

Upvotes: 8

Views: 32002

Answers (4)

user2555451
user2555451

Reputation:

You gave except an instance of an IndexError. Do this instead:

try:
    modrad, thetas = trim_rad(rad)
except IndexError:
    print "Couldn't find main chunk"
    return 0

Here is an example:

>>> try:
...     [1][1]
... except IndexError('no'):
...     pass
...
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
IndexError: list index out of range
>>> try:
...     [1][1]
... except IndexError:
...     pass
...
>>>

Upvotes: 11

Alex
Alex

Reputation: 2013

You seem to be catching the exception wrong. You catch exceptions of type, the notation below will assign the exception to e so you can read the description in your except handler.

try:
    modrad, thetas = trim_rad(rad)
except IndexError as e:
    print e.message
    return 0

Upvotes: 3

Joohwan
Joohwan

Reputation: 2512

change 

except IndexError("Couldn't find main chunk"):

to 

except IndexError:

Upvotes: 3

Sukrit Kalra
Sukrit Kalra

Reputation: 34531

Catch just the IndexError.

try:
    raise IndexError('abc')
except IndexError('abc'):
    print 'a'



Traceback (most recent call last):
  File "<pyshell#22>", line 2, in <module>
    raise IndexError('abc')
IndexError: abc

try:
    raise IndexError('abc')
except IndexError:
    print 'a'


a # Output

So, reduce your code to

try:
    modrad, thetas = trim_rad(rad)
except IndexError:
    return 0

If you want to catch the error message too, use the following syntax:

try:
    raise IndexError('abc')
except IndexError as err:
    print err


abc

Upvotes: 14

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