Custom python Exception with custom message

Question

I want my custom exception be able to print a custom message when it raises. I got this approach (simplifyed):

class BooError(Exception):
    def __init__(self, *args):
        super(BooError, self).__init__(*args)
        self.message = 'Boo'

But the result is not satisfy me:

raise BooError('asdcasdcasd')

Output:

Traceback (most recent call last):
  File "hookerror.py", line 8, in <module>
    raise BooError('asdcasdcasd')
__main__.BooError: asdcasdcasd

I expected something like:

...
__main__.BooError: Boo

I know about message is deprecated. But I do not know what is the correct way to customize error message?

In what way does the result not satisfy you? What is the result you want? — BrenBarn
– BrenBarn, Commented Jan 15, 2014 at 18:59
maybe add a return self.message statement at the bottom of the __init__ method? This is probably bad style, but might work :) — Peter Lustig
– Peter Lustig, Commented Jan 15, 2014 at 19:07
stackoverflow.com/questions/6180185/… seems to contain the answer you are looking for! — Peter Lustig
– Peter Lustig, Commented Jan 15, 2014 at 19:09
@PeterLustig Id suggest the answer by Aditya Satyavada that's currently all the way at the bottom. — Bobdabear
– Bobdabear, Commented Aug 15, 2023 at 16:48

Martijn Pieters · Accepted Answer · 2014-01-15 19:14:22Z

2

You'll need to set the args tuple as well:

class BooError(Exception):
    def __init__(self, *args):
        super(BooError, self).__init__(*args)
        self.args = ('Boo',)
        self.message = self.args[0]

where self.message is normally set from the first args item. The message attribute is otherwise entirely ignored by the Exception class.

You'd be far better off passing the argument to __init__:

class BooError(Exception):
    def __init__(self, *args):
        super(BooError, self).__init__('Boo')

edited Jan 15, 2014 at 19:14

answered Jan 15, 2014 at 19:08

Martijn Pieters

1.1m326 gold badges4.2k silver badges3.4k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Alvaro Over a year ago

Why not pass it as parameter of super init?

Markku K. Over a year ago

Alternatively, he could just do super(BooError, self).__init__('Boo')

Collectives™ on Stack Overflow

Custom python Exception with custom message

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related