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Re: Delegation in Python

References <FeCdnXdsTpunvlnJnZ2dnUVZ8judnZ2d@brightview.co.uk> <mailman.18106.1422141738.18130.python-list@python.org> <5ZKdnd6rbdZ3sVnJnZ2dnUVZ8mCdnZ2d@brightview.co.uk>
Date 2015-01-25 10:43 +1100
Subject Re: Delegation in Python
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.18109.1422143020.18130.python-list@python.org> (permalink)

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On Sun, Jan 25, 2015 at 10:38 AM, Brian Gladman <noone@nowhere.net> wrote:
> On 24/01/2015 23:22, Chris Angelico wrote:
>> class RF(Fraction):
>>     def is_integer(self):
>>        return self.numerator % self.denominator == 0
>
> Thanks for your help on this.  I must admit that nowhere in a lot of
> searching did I find that delegation is achieved by doing nothing!

Hehe :) If you want a technical look at it, what you have is the
fundamental nature of subclassing: you derive from another class, and
your class is identical to that with certain exceptions (in your case,
an additional method). Python's way of handling that is called the
Method Resolution Order or MRO, and you can find info on it on the
web, eg:

http://python-history.blogspot.com/2010/06/method-resolution-order.html

Enjoy!

ChrisA

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Thread

Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-24 22:57 +0000
  Re: Delegation in Python Chris Angelico <rosuav@gmail.com> - 2015-01-25 10:22 +1100
    Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-24 23:38 +0000
      Re: Delegation in Python Chris Angelico <rosuav@gmail.com> - 2015-01-25 10:43 +1100
        Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-25 00:18 +0000
          Re: Delegation in Python Chris Angelico <rosuav@gmail.com> - 2015-01-25 11:28 +1100
            Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-25 07:49 +0000
              Re: Delegation in Python Chris Angelico <rosuav@gmail.com> - 2015-01-25 19:07 +1100
      Re: Delegation in Python Gary Herron <gherron@digipen.edu> - 2015-01-24 15:47 -0800
        Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-24 23:58 +0000
  Re: Delegation in Python Gary Herron <gherron@digipen.edu> - 2015-01-24 15:41 -0800
    Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-24 23:52 +0000
  Re: Delegation in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-01-24 23:59 +0000
  Re: Delegation in Python Chris Angelico <rosuav@gmail.com> - 2015-01-25 11:07 +1100
  Re: Delegation in Python Terry Reedy <tjreedy@udel.edu> - 2015-01-24 20:31 -0500
    Re: Delegation in Python Brian Gladman <noone@nowhere.net> - 2015-01-25 07:43 +0000

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