[Python-Dev] Is static typing still optional?

[Eric V. Smith]

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, 
which they would not be if hash=False were the default. If there's some 
case there that you disagree with, I'd be interested in hearing about it.

That logic is what is currently scheduled to go in to 3.7 beta 1. I have 
not updated the PEP yet, mostly because it's so difficult to explain.

What's the case where setting hash=False causes it to be hashable? I 
don't think that was ever the case, and I hope it's not the case now.

Eric