lenskit.data.accum.AccumulatorFactory#

classlenskit.data.accum.AccumulatorFactory[X, R]#

Bases: Protocol

Base class for protocol classes.

Protocol classes are defined as:

classProto(Protocol):
 defmeth(self) -> int:
 ...

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

For example:

classC:
 defmeth(self) -> int:
 return 0
deffunc(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:

classGenProto[T](Protocol):
 defmeth(self) -> T:
 ...
create_accumulator()#

Create an accumulator for the results of this object.

Returns:

An accumulator.

Return type:

Accumulator[X, R]