youngoli commented on a change in pull request #12903: URL: https://github.com/apache/beam/pull/12903#discussion_r495407788
########## File path: sdks/go/pkg/beam/core/runtime/genx/genx.go ########## @@ -0,0 +1,172 @@ +// 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 genx is a convenience package to better support the code +// generator. It can be depended on by the user facing beam package +// and be refered to by generated code. +// +// Similarly, it can depend on beam internals and access the canonical +// method list in the graph package, or other packages to filter out +// types that aren't necessary for registration (like context.Context). +package genx + +import ( + "reflect" + + "github.com/apache/beam/sdks/go/pkg/beam/core/funcx" + "github.com/apache/beam/sdks/go/pkg/beam/core/graph" + "github.com/apache/beam/sdks/go/pkg/beam/core/runtime" +) + +// RegisterDoFn is a convenience function for registering DoFns. +// Differs from RegisterFunction and RegisterType by introspecting +// all parameters and returns of Lifecycle methods on the dofn, +// and registers those types for you. +// +// Panics if not passed a dofn. +func RegisterDoFn(dofn interface{}) { + f, ts, err := registerDoFn(dofn) + if err != nil { + panic(err) + } + if f != nil { + runtime.RegisterFunction(f) + } + for _, t := range ts { + runtime.RegisterType(t) + } +} + +// registerDoFn returns all types associated with the provided DoFn. +// If passed a functional DoFn, the first return is a Function to +// register with runtime.RegisterFunction. +// The second return is all types to register with runtime.RegisterType. +// Returns an error if the passed in values are not DoFns. +func registerDoFn(dofn interface{}) (interface{}, []reflect.Type, error) { + if rt, ok := dofn.(reflect.Type); ok { + if rt.Kind() == reflect.Ptr { + rt = rt.Elem() + } + dofn = reflect.New(rt).Interface() Review comment: Oh, duh. I had a brain-fart that this statement only happens if the dofn is a reflect.Type. I was imagining turning an actual DoFn instance into a reflect.Type and back. Makes complete sense now. ---------------------------------------------------------------- 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]
