lenskit.data.accum.AccumulatorFactory
=====================================

.. py:class:: lenskit.data.accum.AccumulatorFactory[X, R]
   :canonical: lenskit.data.accum._proto.AccumulatorFactory

   Bases: :py:obj:`Protocol`


   Base class for protocol classes.

   Protocol classes are defined as::

       class Proto(Protocol):
           def meth(self) -> int:
               ...

   Such classes are primarily used with static type checkers that recognize
   structural subtyping (static duck-typing).

   For example::

       class C:
           def meth(self) -> int:
               return 0

       def func(x: Proto) -> int:
           return x.meth()

       func(C())  # Passes static type check

   See PEP 544 for details. Protocol classes decorated with
   @typing.runtime_checkable act as simple-minded runtime protocols that check
   only the presence of given attributes, ignoring their type signatures.
   Protocol classes can be generic, they are defined as::

       class GenProto[T](Protocol):
           def meth(self) -> T:
               ...


   .. py:method:: create_accumulator()

      Create an accumulator for the results of this object.

      :returns: An accumulator.