[Python-Dev] One-line abstractmethod function?

Ethan Furman ethan at stoneleaf.us
Thu Dec 5 21:43:10 CET 2013

On 12/05/2013 12:39 PM, MRAB wrote:
> On 05/12/2013 19:22, Ethan Furman wrote:
>> On 12/05/2013 10:56 AM, Alexander Belopolsky wrote:
>>> On Thu, Dec 5, 2013 at 1:24 PM, Guido van Rossum wrote:
>>>> How would you get the docstrings in? [...]
>>> One way to reduce the amount of boilerplate code is to make abstractmethod
>>> to supply raise NotImplementedError body when none is given.  Then you can
>>>  write
>>> class Foo:
>>>      @abc.abstractmethod
>>>      def do_bar(self):
>>>           """perform bar"""
>>> The docstring will be required when skipping the body which is probably a good thing.
>> How will abstractmethod know its function has no body?
> An abstract method won't have a body (I'm not counting the docstring).
> If it _does_ have a body, then it's _not_ an abstract method!

To quote the docs [1]:

> Note
> Unlike Java abstract methods, these abstract methods may have an implementation.
>  This implementation can be called via the super() mechanism from the class that
>  overrides it. This could be useful as an end-point for a super-call in a framework
>  that uses cooperative multiple-inheritance.


[1] http://docs.python.org/dev/library/abc.html

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