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Re: Multiple inheritance, super() and changing signature

From Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups comp.lang.python
Subject Re: Multiple inheritance, super() and changing signature
Date 2016-06-03 08:39 -0600
Message-ID <mailman.126.1464964789.1839.python-list@python.org> (permalink)
References (1 earlier) <mailman.54.1464711627.1839.python-list@python.org> <574e45f4$0$1611$c3e8da3$5496439d@news.astraweb.com> <a17955cb-04d3-9dd6-e2b3-4719269f241d@shopzeus.com> <d91f49c5-4572-9cc4-9688-b4b3ffbce691@shopzeus.com> <CALwzidnc=Yws6gSOpt_spYWGTJkq4zOuUmcVNuyF6Xuv3dK++Q@mail.gmail.com>

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On Fri, Jun 3, 2016 at 8:06 AM, Nagy László Zsolt <gandalf@shopzeus.com> wrote:
>
>>> That's overly strict. As Raymond shows, it is easy to deal with
>>> changing method signatures in *cooperative* classes.
>> I must watch that for sure.
>
> All right, I have read this:
>
> https://rhettinger.wordpress.com/2011/05/26/super-considered-super/
>
> There is still something I don't get: how to create cooperative classes
> when some base classes share some of the parameters?

Why do they need to share the same parameter? Part of cooperative
design is that you can't really design each class in a vacuum; you
need to take the other classes they might get combined with into
account. Perhaps you can extract that parameter into another base
class that is shared by both:

class Root:
    def __init__(self, *, param1, **kwds):
        self.param1 = param1
        super().__init__(**kwds)

class A(Root):
    def __init__(self, *, param2, **kwds):
        self.param2 = param2
        super().__init__(**kwds)

class B(Root):
    def __init__(self, *, param3, **kwds):
        self.param3 = param3
        super().__init__(**kwds)

class X(A, B):
    pass

A and B can both depend on having param1 without stomping on each
other because they both inherit Root which requires it.

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Thread

Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-05-31 18:10 +0200
  Re: Multiple inheritance, super() and changing signature Steven D'Aprano <steve@pearwood.info> - 2016-06-01 12:18 +1000
    Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-03 14:10 +0200
      Re: Multiple inheritance, super() and changing signature Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-04 13:06 +1200
        Re: Multiple inheritance, super() and changing signature Steven D'Aprano <steve@pearwood.info> - 2016-06-04 12:51 +1000
          Re: Multiple inheritance, super() and changing signature Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-04 23:50 +1200
        Re: Multiple inheritance, super() and changing signature Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-03 23:05 -0600
          Re: Multiple inheritance, super() and changing signature Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-04 23:52 +1200
            Re: Multiple inheritance, super() and changing signature Steven D'Aprano <steve@pearwood.info> - 2016-06-04 23:46 +1000
              Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-04 16:42 +0200
    Re: Multiple inheritance, super() and changing signature Ben Finney <ben+python@benfinney.id.au> - 2016-06-03 22:21 +1000
      Re: Multiple inheritance, super() and changing signature Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-04 13:10 +1200
    Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-03 14:14 +0200
    Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-03 14:57 +0200
    Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-03 16:06 +0200
    Re: Multiple inheritance, super() and changing signature Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-03 08:39 -0600
    Re: Multiple inheritance, super() and changing signature Michael Selik <michael.selik@gmail.com> - 2016-06-03 15:33 +0000
    Re: Multiple inheritance, super() and changing signature Nagy László Zsolt <gandalf@shopzeus.com> - 2016-06-03 17:59 +0200
    Re: Multiple inheritance, super() and changing signature Michael Selik <michael.selik@gmail.com> - 2016-06-03 16:28 +0000
    Re: Multiple inheritance, super() and changing signature Ben Finney <ben+python@benfinney.id.au> - 2016-06-04 06:16 +1000
    Re: Multiple inheritance, super() and changing signature Ben Finney <ben+python@benfinney.id.au> - 2016-06-04 06:19 +1000
    Re: Multiple inheritance, super() and changing signature Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-03 15:53 -0600
    Re: Multiple inheritance, super() and changing signature Ben Finney <ben+python@benfinney.id.au> - 2016-06-04 10:44 +1000

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