lostluck commented on code in PR #1:
URL: https://github.com/apache/beam-starter-go/pull/1#discussion_r898622963
##########
main.go:
##########
@@ -0,0 +1,44 @@
+package main
+
+import (
+ "context"
+ "flag"
+ "fmt"
+ "log"
+
+ "github.com/apache/beam/sdks/v2/go/pkg/beam"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
+)
+
+var (
+ input_text = flag.String("input-text", "Default input text", "Input
text to print.")
+)
+
+type Result = struct {
+ Pipeline *beam.Pipeline
+ Scope beam.Scope
+ PCollection beam.PCollection
+}
+
+func my_pipeline(input_text string) Result {
+ beam.Init()
Review Comment:
This should be called in `main`, right after flag parsing.
##########
main.go:
##########
@@ -0,0 +1,44 @@
+package main
+
+import (
+ "context"
+ "flag"
+ "fmt"
+ "log"
+
+ "github.com/apache/beam/sdks/v2/go/pkg/beam"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
+)
+
+var (
+ input_text = flag.String("input-text", "Default input text", "Input
text to print.")
+)
+
+type Result = struct {
+ Pipeline *beam.Pipeline
+ Scope beam.Scope
+ PCollection beam.PCollection
+}
+
+func my_pipeline(input_text string) Result {
+ beam.Init()
+
+ pipeline, scope := beam.NewPipelineWithRoot()
+
+ elements := beam.Create(scope, "Hello", "World!", input_text)
+ elements = beam.ParDo(scope, func(elem string, emit func(string)) {
fmt.Println(elem); emit(elem) }, elements)
Review Comment:
While an anonymous function *can* work in Beam Go, it will cause more
trouble than it's worth. Move it to a standard definition, and use an init
block to register the function.
Otherwise, folks moving beyond the direct runner will have a bad time.
```
func printAndEmit(elem string, emit(string)) {
fmt.Println(elem)
emit(elem)
}
func init() {
// DoFns should be registered with Beam.
beam.RegisterFunction(printAndEmit)
}
```
##########
main.go:
##########
@@ -0,0 +1,44 @@
+package main
+
+import (
+ "context"
+ "flag"
+ "fmt"
+ "log"
+
+ "github.com/apache/beam/sdks/v2/go/pkg/beam"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
+)
+
+var (
+ input_text = flag.String("input-text", "Default input text", "Input
text to print.")
+)
+
+type Result = struct {
Review Comment:
Secondly, while one *can* define a type for this, one shouldn't. Go would
just use multiple returns.
In this case, I would recommend calling `pipeline, scope :=
beam.NewPipelineWithRoot()` in `main`, and passing in the scope variable. Then
we simply return the PCollection.
##########
main.go:
##########
@@ -0,0 +1,44 @@
+package main
+
+import (
+ "context"
+ "flag"
+ "fmt"
+ "log"
+
+ "github.com/apache/beam/sdks/v2/go/pkg/beam"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/x/beamx"
+)
+
+var (
+ input_text = flag.String("input-text", "Default input text", "Input
text to print.")
+)
+
+type Result = struct {
Review Comment:
Type definitions don't use an `=`. Using an equal defines a type alias,
which isn't what we want here.
```suggestion
type Result struct {
```
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