[Python-Dev] Make __class_getitem__ a class method

[Serhiy Storchaka]

15.12.17 18:47, Yury Selivanov пише:
> Shouldn't we optimize the usability for pure-Python first, and then for C API?
> 
> Right now we have the '__new__' magic method, which isn't a
> @classmethod.  Making '__class_getitem__' a @classmethod will confuse
> regular Python users.  For example:
> 
>     class Foo:
>        def __new__(cls, ...): pass
> 
>        @classmethod
>        def __class_getitem__(cls, item): pass
> 
> To me it makes sense that type methods that are supposed to be called
> on type by the Python interpreter don't need the classmethod
> decorator.
> 
> METH_STATIC is a public working API, and in my opinion it's totally
> fine if we use it. It's not even hard to use it, it's just *mildly*
> inconvenient at most.

__new__ is not a class method, it is an "automatic" static method.

 >>> class C:
...     def __new__(cls): return object.__new__(cls)
...
 >>> C().__new__ is C.__new__
True
 >>> C.__dict__['__new__']
<staticmethod object at 0x7f664ae82c20>

The following two declarations are equivalent:

class A:
     def __new__(cls): return cls.__name__

class B:
     @staticmethod
     def __new__(cls): return cls.__name__