[Python-ideas] Optional static typing -- the crossroads

[Łukasz Langa]

On Aug 15, 2014, at 5:26 PM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

> Łukasz Langa wrote:
> 
>> class C:
>>  cls_member: str = ‘on the class’
>>  def __init__(self):
>>    self.obj_member: str = ‘on the instance'
>>    self.cls_member = 2   # that’s the real question: type error or an instance member?
> 
> I think not treating it as an error would make it hard
> to reason about the type of x.cls_member for an instance
> x of C. Its type would depend on whether del x.cls_member
> had been performed on x.
> 
> Code which relied on them being different types would
> be rather confusing to a human reader too, so it's
> probably fine to discourage that.

That was my reasoning exactly. +1

-- 
Best regards,
Łukasz Langa

WWW: http://lukasz.langa.pl/
Twitter: @llanga
IRC: ambv on #python-dev

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