[Python-Dev] Concerns about method overriding and subclassing with dataclasses

[Eric V. Smith]

I’m traveling until next week, and haven’t had time to read any of these emails. I’ll look at them when I return. 

--
Eric.

> On Dec 30, 2017, at 5:20 AM, Raymond Hettinger <raymond.hettinger at gmail.com> wrote:
> 
> 
>> On Dec 29, 2017, at 4:52 PM, Guido van Rossum <guido at python.org> wrote:
>> 
>> I still think it should overrides anything that's just inherited but nothing that's defined in the class being decorated.
> 
> This has the virtue of being easy to explain, and it will help with debugging by honoring the code proximate to the decorator :-)
> 
> For what it is worth, the functools.total_ordering class decorator does something similar -- though not exactly the same.  A root comparison method is considered user-specified if it is different than the default method provided by object: 
> 
>    def total_ordering(cls):
>        """Class decorator that fills in missing ordering methods"""
>        # Find user-defined comparisons (not those inherited from object).
>        roots = {op for op in _convert if getattr(cls, op, None) is not getattr(object, op, None)}
>        ...
> 
> The @dataclass decorator has a much broader mandate and we have almost no experience with it, so it is hard to know what legitimate use cases will arise.
> 
> 
> Raymond
> 
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