lostluck commented on a change in pull request #15057: URL: https://github.com/apache/beam/pull/15057#discussion_r662652348
########## File path: sdks/go/examples/snippets/04transforms.go ########## @@ -0,0 +1,289 @@ +// 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. + +package snippets + +import ( + "fmt" + "math" + "reflect" + "sort" + "strings" + + "github.com/apache/beam/sdks/go/pkg/beam" + "github.com/apache/beam/sdks/go/pkg/beam/transforms/stats" +) + +// [START model_pardo_pardo] + +// ComputeWordLengthFn is the DoFn to perform on each element in the input PCollection. +type ComputeWordLengthFn struct{} + +// ProcessElement is the method to execute for each element. +func (fn *ComputeWordLengthFn) ProcessElement(word string, emit func(int)) { Review comment: I'm largely basing it on the Java approach which has the output context object, rather than the python one. Generally users will need to know the arbitrary emitters, for more complex DoFns. The simple return case is a convenience but 1:1 is incredibly limiting. If users don't find it, they won't hurt themselves by not knowing it. The section is outputting multiple PCollections, not multiple elements within a PCollection. Similarly, that's why I didn't introduce it using a functional DoFn. It leads to users assuming closures can work for configuration, which can't work in Go at the moment. Structural DoFns are not the most convenient, but they are the most versatile. They prevent errors like closure functions, which are far harder to debug when they sometimes work and fail otherwise. -- 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]
