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Hi,

environment: Python 2.4, GNU/Linux, kernel 2.6.12.2

having subclassed 'Exception' I'm trying to call the initialiser
__init__(...) of the superclass Exception with 'super(..).__init__(..)' .
However, trying to do so results in a
'TypeError: super() argument 1 must be type, not classobj'.

Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything
works just as one would expect.

Why does 'super(..).__init__(..)' fail?


thank you for any suggestions
chriss



Here is some example code to illustrate the point:


class WorkingException(Exception):

def __init__(self, message):
# works as I would expect
Exception.__init__(self, message)


class BrokenException(Exception):

def __init__(self, message):
# fails with a typeError
super(BrokenException, self).__init__(self, message)


# --------- case 1 ---------
try:
raise WorkingException("Hello WorkingException")

except WorkingException, e:
print e


# --------- case 3 ---------

try:
raise BrokenException("Hello BrokenException")


except BrokenException, e:
print e

chriss wrote:
> Hi,
>
> environment: Python 2.4, GNU/Linux, kernel 2.6.12.2
>
> having subclassed 'Exception' I'm trying to call the initialiser
> __init__(...) of the superclass Exception with 'super(..).__init__(..)' .
> However, trying to do so results in a
> 'TypeError: super() argument 1 must be type, not classobj'.
>
> Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything
> works just as one would expect.
>
> Why does 'super(..).__init__(..)' fail?

AFAICT, the Exception hierarchy are still old-style classes while
super() only works on new-style classes.

--
Robert Kern


"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

chriss wrote:
> Hi,
>
> environment: Python 2.4, GNU/Linux, kernel 2.6.12.2
>
> having subclassed 'Exception' I'm trying to call the initialiser
> __init__(...) of the superclass Exception with 'super(..).__init__(..)' .
> However, trying to do so results in a
> 'TypeError: super() argument 1 must be type, not classobj'.
>
> Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything
> works just as one would expect.
>
> Why does 'super(..).__init__(..)' fail?

Exceptions do not inherit from 'object'; they are old-style classes.

super() can be used only with new-style classes (which subclass 'object').

-Peter

Peter Hansen wrote:

> chriss wrote:
>> Hi,
>>
>> environment: Python 2.4, GNU/Linux, kernel 2.6.12.2
>>
>> having subclassed 'Exception' I'm trying to call the initialiser
>> __init__(...) of the superclass Exception with 'super(..).__init__(..)' .
>> However, trying to do so results in a
>> 'TypeError: super() argument 1 must be type, not classobj'.
>>
>> Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything
>> works just as one would expect.
>>
>> Why does 'super(..).__init__(..)' fail?
>
> Exceptions do not inherit from 'object'; they are old-style classes.
>
> super() can be used only with new-style classes (which subclass 'object').
>
> -Peter

That explains it all right.
Thank you very much for your answer.

chriss