def __init__(self, name, coder=None, combine_fn=None):
# type: (str, Optional[Coder], Any) -> None
"""Initialize the specification for CombiningValue state.
CombiningValueStateSpec(name, combine_fn) -> Coder-inferred combining value
state spec.
CombiningValueStateSpec(name, coder, combine_fn) -> Combining value state
spec with coder and combine_fn specified.
Args:
name (str): The name by which the state is identified.
coder (Coder): Coder specifying how to encode the values to be combined.
May be inferred.
combine_fn (``CombineFn`` or ``callable``): Function specifying how to
combine the values passed to state.
"""
# Avoid circular import.
from apache_beam.transforms.core import CombineFn
# We want the coder to be optional, but unfortunately it comes
# before the non-optional combine_fn parameter, which we can't
# change for backwards compatibility reasons.
#
# Instead, allow it to be omitted (by either passing two arguments
# or combine_fn by keyword.)
if combine_fn is None:
if coder is None:
raise ValueError('combine_fn must be provided')
else:
coder, combine_fn = None, coder
self.combine_fn = CombineFn.maybe_from_callable(combine_fn)
# The coder here should be for the accumulator type of the given CombineFn.
if coder is None:
coder = self.combine_fn.get_accumulator_coder()
super(CombiningValueStateSpec, self).__init__(name, coder)
def __init__(self, name, coder, combine_fn):
# Avoid circular import.
from apache_beam.transforms.core import CombineFn
assert isinstance(name, str)
assert isinstance(coder, Coder)
self.name = name
# The coder here should be for the accumulator type of the given CombineFn.
self.coder = coder
self.combine_fn = CombineFn.maybe_from_callable(combine_fn)
def __init__(self, name, coder, combine_fn):
# Avoid circular import.
from apache_beam.transforms.core import CombineFn
assert isinstance(name, str)
assert isinstance(coder, Coder)
self.name = name
# The coder here should be for the accumulator type of the given CombineFn.
self.coder = coder
self.combine_fn = CombineFn.maybe_from_callable(combine_fn)