python customize existing built-in exception

Question

For example in this code, I want my script behavior this way.

when run to b=a[2], or any line will raise an exception, and no matter what is the exception. I want the script stop, and raise a customized red error message like: 'LOL!!!'

How to implement that?

try:
    a = [1,2]
    b = a[2]
except:
    raise something

Chris Arena · Accepted Answer · 2014-07-04 06:32:42Z

5

try:
    a = [1,2]
    b = a[2]
except IndexError:
    raise Exception('LOL!')

This works because the stament a[2] throws an IndexError. There are only 2 elements in a, and a[2] fetches the third (counting from zero).

... Alright...

class YourCustomException(Exception):
    pass

try:
    a = [1,2]
    raise YourCustomException('LOL')
except YourCustomException:
    print('NOW WHAT?')

edited Jul 4, 2014 at 6:32

answered Jul 4, 2014 at 5:41

Chris Arena

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1 Comment

MacSanhe Over a year ago

thank you. But it's not the answer I need. I mean, the Exception are not able to predict. I need a method to raise my custom exception message, and no matter what it is the original exception.

Netro · Accepted Answer · 2014-07-04 05:44:45Z

0

You should read about raising exception at https://docs.python.org/2/reference/simple_stmts.html#raise

Exception hirearchy is https://docs.python.org/2/library/exceptions.html#exception-hierarchy

Here is your required answer,

try:
    a = [1,2]
    b = a[2]
#except Exception:
except IndexError: 
    raise Exception("Lol")

answered Jul 4, 2014 at 5:44

Netro

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