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Re: Python's super() considered super!

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Ethan Furman <ethan@stoneleaf.us> wrote:

>>>>> foo(x=1, y=2, z=3)
>> Traceback (most recent call last):
>>   File "<pyshell#8>", line 1, in <module>
>>     foo(x=1, y=2, z=3)
>>   File "<pyshell#4>", line 2, in foo
>>     bar(y=2, **kwargs)
>> TypeError: bar() got multiple values for keyword argument 'y'
> 
> And the above error is exactly why you don't want to use named arguments 
> in MI -- because you don't know in what order the methods will be 
> called, you cannot know which named arguments to supply to the method 
> that super() will call next.
> 

No, it just means you have to be careful how you do it: if you want to pass 
'y' to a super call then you must pop it out of the arguments. This can be 
done as easily with a named argument as with an explicit 'pop()' on kwargs.

What using a named argument does it to change the default action from 
silently overwriting any argumement passing up the chain to raising an 
error if you attempt to overwrite it without first checking whether it 
exists.

-- 
Duncan Booth http://kupuguy.blogspot.com

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Python's super() considered super! Raymond Hettinger <python@rcn.com> - 2011-05-26 09:31 -0700
  Re: Python's super() considered super! Raymond Hettinger <python@rcn.com> - 2011-05-26 09:39 -0700
    Re: Python's super() considered super! Dotan Cohen <dotancohen@gmail.com> - 2011-05-26 21:13 +0300
    Re: Python's super() considered super! Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-26 12:38 -0600
    Re: Python's super() considered super! Dotan Cohen <dotancohen@gmail.com> - 2011-05-26 21:56 +0300
    Re: Python's super() considered super! Terry Reedy <tjreedy@udel.edu> - 2011-05-26 16:15 -0400
  Re: Python's super() considered super! Ben Finney <ben+python@benfinney.id.au> - 2011-05-27 11:39 +1000
    Re: Python's super() considered super! Raymond Hettinger <python@rcn.com> - 2011-05-27 00:16 -0700
      Re: Python's super() considered super! Ben Finney <ben+python@benfinney.id.au> - 2011-05-27 18:49 +1000
        Re: Python's super() considered super! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-27 10:37 +0000
          Re: Python's super() considered super! Duncan Booth <duncan.booth@invalid.invalid> - 2011-05-27 10:53 +0000
            Re: Python's super() considered super! Ethan Furman <ethan@stoneleaf.us> - 2011-05-27 10:42 -0700
              Re: Python's super() considered super! Duncan Booth <duncan.booth@invalid.invalid> - 2011-05-30 09:18 +0000
    RE: Python's super() considered super! "Prasad, Ramit" <ramit.prasad@jpmchase.com> - 2011-05-27 14:10 -0400
    Re: Python's super() considered super! Chris Angelico <rosuav@gmail.com> - 2011-05-28 04:40 +1000
  Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 07:27 -0700
    Re: Python's super() considered super! Mel <mwilson@the-wire.com> - 2011-05-27 10:33 -0400
      Re: Python's super() considered super! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-27 14:49 +0000
        Re: Python's super() considered super! harrismh777 <harrismh777@charter.net> - 2011-05-27 10:07 -0500
    Re: Python's super() considered super! Duncan Booth <duncan.booth@invalid.invalid> - 2011-05-27 15:05 +0000
      Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 08:24 -0700
      Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 08:31 -0700
        Re: Python's super() considered super! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-27 16:06 +0000
          Re: Python's super() considered super! Stefan Behnel <stefan_ml@behnel.de> - 2011-05-27 23:49 +0200
            Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 16:57 -0700
              Re: Python's super() considered super! Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-05-28 07:29 +0200
          Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 17:04 -0700
      Re: Python's super() considered super! Ryan Kelly <ryan@rfk.id.au> - 2011-05-28 09:57 +1000
    Re: Python's super() considered super! sturlamolden <sturlamolden@yahoo.no> - 2011-05-27 08:11 -0700
  Re: Python's super() considered super! Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-27 12:31 -0600
  Re: Python's super() considered super! Chris Angelico <rosuav@gmail.com> - 2011-05-28 04:46 +1000
    Re: Python's super() considered super! John Nagle <nagle@animats.com> - 2011-05-27 13:47 -0700
  Re: Python's super() considered super! Ethan Furman <ethan@stoneleaf.us> - 2011-05-27 15:24 -0700

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