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Groups > comp.lang.python > #27186

Re: Dynamically determine base classes on instantiation

Date 2012-08-16 19:27 +0200
From Thomas Bach <thbach@students.uni-mainz.de>
Subject Re: Dynamically determine base classes on instantiation
References (1 earlier) <502c3bc2$0$29978$c3e8da3$5496439d@news.astraweb.com> <mailman.3358.1345121602.4697.python-list@python.org> <502d0d74$0$6986$e4fe514c@news2.news.xs4all.nl> <mailman.3382.1345136056.4697.python-list@python.org> <ef388942-5cef-45cd-9c79-6e4a7f2f613a@googlegroups.com>
Newsgroups comp.lang.python
Message-ID <mailman.3385.1345138122.4697.python-list@python.org> (permalink)

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On Thu, Aug 16, 2012 at 10:03:51AM -0700, Richard Thomas wrote:
> class Foo(object):
>     def __new__(cls, arg):
>         if isinstance(arg, list):
>             cls = FooList
>         elif isinstance(arg, dict):
>             cls = FooDict
>         return object.__new__(cls, arg)
> 
> class FooList(Foo, list):
>     pass
> 
> class FooDict(Foo, dict):
>     pass
> 
> You could even have __new__ make these Foo* classes dynamically when
> it encounters a new type of argument.
> 
> Chard.

Thanks for that one. Your solution just hit me like a punch in the
face. I had something similar in my mind. But I could not work out how
the mechanics behind it are working.

Regards,

	Thomas

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Thread

Dynamically determine base classes on instantiation Thomas Bach <thbach@students.uni-mainz.de> - 2012-08-15 23:17 +0200
  Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-16 00:16 +0000
    Re: Dynamically determine base classes on instantiation Thomas Bach <thbach@students.uni-mainz.de> - 2012-08-16 14:52 +0200
      Re: Dynamically determine base classes on instantiation Hans Mulder <hansmu@xs4all.nl> - 2012-08-16 17:10 +0200
        Re: Dynamically determine base classes on instantiation Thomas Bach <thbach@students.uni-mainz.de> - 2012-08-16 18:54 +0200
          Re: Dynamically determine base classes on instantiation Richard Thomas <chardster@gmail.com> - 2012-08-16 10:03 -0700
            Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-16 17:49 +0000
              Re: Dynamically determine base classes on instantiation Richard Thomas <chardster@gmail.com> - 2012-08-17 04:50 -0700
                Re: Dynamically determine base classes on instantiation Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-17 14:53 -0400
                Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-18 01:44 +0000
                Re: Dynamically determine base classes on instantiation Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-18 11:36 +0100
          Re: Dynamically determine base classes on instantiation Richard Thomas <chardster@gmail.com> - 2012-08-16 10:03 -0700
            Re: Dynamically determine base classes on instantiation Thomas Bach <thbach@students.uni-mainz.de> - 2012-08-16 19:27 +0200
      Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-16 18:04 +0000
    Re: Dynamically determine base classes on instantiation Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-16 12:29 -0400
    Re: Dynamically determine base classes on instantiation Richard Thomas <chardster@gmail.com> - 2012-08-16 10:09 -0700
      Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-16 17:45 +0000
    Re: Dynamically determine base classes on instantiation Thomas Bach <thbach@students.uni-mainz.de> - 2012-08-16 19:18 +0200
      Re: Dynamically determine base classes on instantiation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-16 18:08 +0000

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