Interface and duck typing woes

[Ned Batchelder]

On 8/30/13 8:13 PM, Steven D'Aprano wrote:
> On Fri, 30 Aug 2013 06:35:47 -0400, Roy Smith wrote:
>
>> In article <52200699$0$6599$c3e8da3$5496439d at news.astraweb.com>,
>>   Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>>
>>> These days, it would be relatively simple to implement pre- and post-
>>> condition checking using decorators, and indeed one of the motivating
>>> use- cases for function annotations in Python 3 is to allow such
>>> things.
>>>
>>> http://www.python.org/dev/peps/pep-3107/
>>>
>>> (Function annotations are perhaps the best Python feature that nobody
>>> uses.)
>> This is awesome.
>
> Heh, everybody has one of two reactions:
>
> "This is awesome!"
>
> "You'll add type checking to my Python code over my dead body!!!"
>
> But I'm still to see a practical use for annotations in real world code.
> Or indeed to think of a use for them other than type checking.
>
>

At PyCon 2007 (I think), Guido was giving a keynote about the features 
coming in Py3k, and he couldn't remember the name "function 
annotations." He said, "what are they called, the things that aren't 
type declarations."

--Ned.