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Groups > comp.lang.python > #109449

Re: Multiple inheritance, super() and changing signature

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Nagy László Zsolt wrote:
> I do not use diamond shapes in my hierarchy, I guess that does not
> affect me. I may be wrong.

If there are no diamonds, there is no need to use super.
Explicit inherited method calls, done correctly, will
work fine.

The only downside is that if your inheritance hierarchy
changes, you need to review all your inherited calls
to make sure they're still correct.

The use of super to address that issue seems attractive.
However, super is only applicable if some rather stringent
requirements are met:

1. All the methods must have compatible signatures.

2. Except for 3 below, all classes participating in the
hierarchy must use super for a given method if any of
them do, including any future subclasses.

3. There must be a class at the top of the hierarchy
that does *not* make super calls, to terminate the chain.

4. It must not matter what order the methods in a super
chain are called. This is because you cannot predict
which method a given super call will invoke. It could
belong to a subclass of the class making the call.

If you can't satisfy *all* of these reqirements, then
you can't use super. Sorry, but that's just the way
super is.

-- 
Greg

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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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