[GitHub] [airflow] ashb commented on a change in pull request #15125: Add latest only decorator

[GitBox <gi...@apache.org>]

ashb commented on a change in pull request #15125:
URL: https://github.com/apache/airflow/pull/15125#discussion_r605491675



##########
File path: airflow/example_dags/example_latest_only_decorator.py
##########
@@ -0,0 +1,58 @@
+#
+# 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.
+
+"""Example of the `latest_only` decorator"""
+
+from airflow import DAG
+from airflow.models.baseoperator import BaseOperator
+from airflow.operators.bash import BashOperator
+from airflow.utils.dates import days_ago
+from airflow.utils.decorators import latest_only
+
+
+# [START example]
+class MyLatestOnlyOperator(BaseOperator):  # pylint: disable=missing-class-docstring
+    def __init__(self, latest_only=True, **kwargs):  # pylint: disable=redefined-outer-name
+        self.latest_only = latest_only
+        if self.latest_only:
+            self.message = 'I will skip all but the latest execution'
+        else:
+            self.message = 'I will never skip'
+        super().__init__(**kwargs)
+
+    @latest_only
+    def execute(self, context):
+        print(self.message)
+
+
+class MyBashOnlyOperator(BashOperator):  # pylint: disable=missing-class-docstring
+    @latest_only
+    def execute(self, context):
+        print('I will skip all but the latest execution')
+        super().execute(context=context)

Review comment:
       It would be nice if this could work as
   
   ```
        subclass_example = latest_only(BashOperator(task_id='latest_only_bash_task', bash_command='echo "hello world"'))
   ```
   
   or similar, but I'm not sure if that is realistically achievable.




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