tvalentyn commented on code in PR #31458: URL: https://github.com/apache/beam/pull/31458#discussion_r1633608570
########## sdks/python/apache_beam/examples/snippets/transforms/elementwise/map_context.py: ########## @@ -0,0 +1,84 @@ +# coding=utf-8 +# +# 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. +# + +# pytype: skip-file +# pylint:disable=line-too-long + +# beam-playground: +# name: MapContext +# description: Demonstration of Map transform usage with a context parameters. +# multifile: false +# default_example: false +# context_line: 41 +# categories: +# - Core Transforms +# complexity: BASIC +# tags: +# - transforms +# - strings +# - map + + +def map_context(test=None): + # [START map_context] + import apache_beam as beam + + import random + from contextlib import contextmanager + + @contextmanager + def random_nonce(): + """A context manager which typically would be used with a `with` statement. + + See https://peps.python.org/pep-0343/ + """ + # Setup code here runs once. + # Here we just create a (shared) random value, but in practice one + # could use this to set up network connections, caches, or other + # re-usable state that could require cleanup. + nonce = random.randrange(0, 100) + + # This (re-used) value is passed on every element call. + yield nonce + + # Cleanup/closing code, if any, would go here to be called once the + # processing is done. + + with beam.Pipeline() as pipeline: + plants = ( + pipeline + | 'Gardening plants' >> beam.Create([ + '🍓Strawberry', + '🥕Carrot', + '🍆Eggplant', + '🍅Tomato', + '🥔Potato', + ], + reshuffle=False) + | 'Strip header' >> beam.Map( + lambda text, + a=beam.DoFn.SetupContextParam(random_nonce), + b=beam.DoFn.BundleContextParam(random_nonce): f"{text} {a} {b}") Review Comment: Thanks, LGTM. Good catch about unusable initialized contexts. In the code sample, consider changing one of the context params to such that takes arguments. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
