[Python-ideas] Make None a subclass of int [alternative to iNaN]

[Serhiy Storchaka]

30.09.18 09:05, Ken Hilton пише:
> Reading the iNaN discussion, most of the opposition seems to be that 
> adding iNaN would add a new special value to integers and therefore add 
> new complexity.
> 
> I propose, instead, that we make None a subclass of int (or even a 
> certain value of int) to represent iNaN. Therefore:
> 
>      >>> None + 1, None - 1, None * 2, None / 2, None // 2
>      (None, None, None, nan, None) # mathematical operations on NaN 
> return NaN
>      >>> None & 1, None | 1, None ^ 1
>      # I'm not sure about this one. The following could be plausible:
>      (0, 1, 1)
>      # or this might make more sense, as this *is* NaN we're talking about:
>      (None, None, None)
>      >>> isinstance(None, int)
>      True # the whole point of this idea
>      >>> issubclass(type(None), int)
>      True # no matter whether None *is* an int or just a subclass, this 
> will be true as issubclass(int, int) is True
> 
> I know this is a crazy idea, but I thought it could have some merit, so 
> why not throw it out here?

This will make some errors passing silently (instead of raising a 
TypeError or AttributeError earlier) and either cause errors far from 
the initial place or producing an incorrect result.