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Re: Should one always add super().__init__() to the __init__?

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Chris Angelico <rosuav@gmail.com> writes:

> On Sun, Sep 30, 2012 at 3:17 AM, Steven D'Aprano
> <steve+comp.lang.python@pearwood.info> wrote:
>> No. Only add code that works and that you need. Arbitrarily adding calls
>> to the superclasses "just in case" may not work:
>>
>> py> class Spam(object):
>> ...     def __init__(self, x):
>> ...             self.x = x
>> ...             super(Spam, self).__init__(x)
>> ...
>> py> x = Spam(1)
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>>   File "<stdin>", line 4, in __init__
>> TypeError: object.__init__() takes no parameters
>
> That's because you're subclassing something that doesn't take
> parameters and giving it parameters. Of course that won't work. The
> normal and logical thing to do is to pass on only the parameters that
> you know the parent class expects... but that implies knowing the
> parent, so it's kinda moot.

It is not necesarily calling the parent class. It calls the initializer
of the next class in the MRO order and what class that is depends on the
actual multiple inheritance structure it is used in, which can depend
on subclasses that you don't know yet. This makes it even worse.
-- 
Piet van Oostrum <piet@vanoostrum.org>
WWW: http://pietvanoostrum.com/
PGP key: [8DAE142BE17999C4]

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Should one always add super().__init__() to the __init__? Ramchandra Apte <maniandram01@gmail.com> - 2012-09-29 06:27 -0700
  Re: Should one always add super().__init__() to the __init__? Ramchandra Apte <maniandram01@gmail.com> - 2012-09-29 06:28 -0700
  Re: Should one always add super().__init__() to the __init__? Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-29 10:59 -0600
  Re: Should one always add super().__init__() to the __init__? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-29 17:17 +0000
    Re: Should one always add super().__init__() to the __init__? Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-09-29 14:18 -0400
    Re: Should one always add super().__init__() to the __init__? Chris Angelico <rosuav@gmail.com> - 2012-09-30 04:31 +1000
      Re: Should one always add super().__init__() to the __init__? Piet van Oostrum <piet@vanoostrum.org> - 2012-09-29 17:51 -0400
        Re: Should one always add super().__init__() to the __init__? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-30 04:40 +0000
          Re: Should one always add super().__init__() to the __init__? Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-30 00:08 -0600
            Re: Should one always add super().__init__() to the __init__? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-30 09:34 +0000
              Re: Should one always add super().__init__() to the __init__? Manuel Pégourié-Gonnard <mpg@elzevir.fr> - 2012-09-30 14:04 +0200
      Re: Should one always add super().__init__() to the __init__? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-30 04:37 +0000
        Re: Should one always add super().__init__() to the __init__? Chris Angelico <rosuav@gmail.com> - 2012-09-30 14:53 +1000
        Re: Should one always add super().__init__() to the __init__? Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-30 01:13 -0600
    Re: Should one always add super().__init__() to the __init__? Ramchandra Apte <maniandram01@gmail.com> - 2012-09-29 20:14 -0700
      Re: Should one always add super().__init__() to the __init__? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-30 04:23 +0000
        Re: Should one always add super().__init__() to the __init__? Ramchandra Apte <maniandram01@gmail.com> - 2012-09-29 21:55 -0700
          Re: Should one always add super().__init__() to the __init__? Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-30 00:10 -0600

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