| # | |
| # 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. | |
| # See the License for the specific language governing permissions and | |
| # limitations under the License. | |
| # | |
| """Observable base class for iterables. | |
| For internal use only; no backwards-compatibility guarantees. | |
| """ | |
| # pytype: skip-file | |
| 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 = [] | |
| def register_observer(self, callback): | |
| self.observers.append(callback) | |
| def notify_observers(self, value, **kwargs): | |
| # self.observers is almost always empty | |
| if self.observers: | |
| for o in self.observers: | |
| o(value, **kwargs) |