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[Python-Dev] Is static typing still optional?


On 1/29/2018 3:42 AM, Ethan Furman wrote:
> On 01/28/2018 07:45 AM, Eric V. Smith wrote:
>> On 1/6/2018 5:13 PM, Eric V. Smith wrote:
>>> On 12/10/2017 5:00 PM, Raymond Hettinger wrote:
> 
>>>> 2) Change the default value for "hash" from "None" to "False".? This 
>>>> might take a little effort because there is
>>>> currently an oddity where setting hash=False causes it to be 
>>>> hashable.? I'm pretty sure this wasn't intended ;-)
>>>
>>> I haven't looked at this yet.
>>
>> I think the hashing logic explained in 
>> https://bugs.python.org/issue32513#msg310830 is correct. It uses 
>> hash=None as the
>> default, so that frozen=True objects are hashable
> 
> In a class, `__hash__ = None` means the instances are not hashable... 
> but in a dataclass decorator, `hash=None` means they are?

It means "don't add a __hash__ attribute, and rely on the base class 
value". But maybe it should mean "is not hashable". But in that case, 
how would we specify the "don't add __hash__" case?

Note that "repr=False" means "don't add a __repr__", not "is not 
repr-able". And "init=False" means "don't add a __init__", not "is not 
init-able".

Eric.