PR GH-4906 changed the typing.Generic class hierarchy, leaving an
outdated comment in the library reference. User-defined Generic ABCs now
must get a abc.ABCMeta metaclass from something other than typing.Generic
inheritance.
(cherry picked from commit
d47f0dd2e85ce032aebfedbde18cdb2e728fa79f)
Co-authored-by: M. Eric Irrgang <mei2n@virginia.edu>
def inproduct(v: Vec[T]) -> T: # Same as Iterable[Tuple[T, T]]
return sum(x*y for x, y in v)
-The metaclass used by :class:`Generic` is a subclass of :class:`abc.ABCMeta`.
-A generic class can be an ABC by including abstract methods or properties,
-and generic classes can also have ABCs as base classes without a metaclass
+.. versionchanged:: 3.7
+ :class:`Generic` no longer has a custom metaclass.
+
+A user-defined generic class can have ABCs as base classes without a metaclass
conflict. Generic metaclasses are not supported. The outcome of parameterizing
generics is cached, and most types in the typing module are hashable and
comparable for equality.