yuqian90 commented on a change in pull request #10930: URL: https://github.com/apache/airflow/pull/10930#discussion_r487978763
########## File path: airflow/models/taskmixin.py ########## @@ -0,0 +1,72 @@ +# 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. + +from abc import abstractmethod + + +class TaskMixin: + """ + Mixing implementing common chain methods like >> and <<. + + In the following functions we use: + Task = Union[BaseOperator, XComArg] + No type annotations due to cyclic imports. + """ + + @abstractmethod + def set_upstream(self, other): + """ + Set a task or a task list to be directly upstream from the current task. + """ + raise NotImplementedError() + + @abstractmethod + def set_downstream(self, other): + """ + Set a task or a task list to be directly downstream from the current task. + """ + raise NotImplementedError() + + def __lshift__(self, other): + """ + Implements Task << Task + """ + self.set_upstream(other) + return other + + def __rshift__(self, other): + """ + Implements Task >> Task + """ + self.set_downstream(other) + return other + + def __rrshift__(self, other): + """ + Called for Task >> [Task] because list don't have Review comment: More of a question than a comment, is the docstr correct? Should it be this instead? ``` Called for [Task] << Task because list don't have __rshift__ operators ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
