#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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"""Observable base class for iterables.
For internal use only; no backwards-compatibility guarantees.
"""
# pytype: skip-file
from __future__ import absolute_import
from builtins import object
[docs]class ObservableMixin(object):
"""For internal use only; no backwards-compatibility guarantees.
An observable iterable.
Subclasses need to call self.notify_observers with any object yielded.
"""
def __init__(self):
self.observers = []
[docs] def register_observer(self, callback):
self.observers.append(callback)
[docs] def notify_observers(self, value, **kwargs):
# self.observers is almost always empty
if self.observers:
for o in self.observers:
o(value, **kwargs)