youngoli commented on a change in pull request #12393:
URL: https://github.com/apache/beam/pull/12393#discussion_r461961550
##########
File path: sdks/go/pkg/beam/create.go
##########
@@ -34,31 +34,44 @@ func Create(s Scope, values ...interface{}) PCollection {
}
// CreateList inserts a fixed set of values into the pipeline from a slice or
-// array. It is a convenience wrapper over Create.
+// array. Differently from Create this supports the creation of an empty
+// PCollection.
func CreateList(s Scope, list interface{}) PCollection {
- var ret []interface{}
val := reflect.ValueOf(list)
+ var ret []interface{}
+ for i := 0; i < val.Len(); i++ {
+ ret = append(ret, val.Index(i).Interface())
+ }
if val.Kind() != reflect.Slice && val.Kind() != reflect.Array {
panic(fmt.Sprintf("Input %v must be a slice or array", list))
}
- for i := 0; i < val.Len(); i++ {
- ret = append(ret, val.Index(i).Interface())
+ if val.Len() == 0 {
+ t := reflect.TypeOf(list).Elem()
+ return Must(TryCreateList(s, t, ret))
}
- return Must(TryCreate(s, ret...))
+ t := reflect.ValueOf(ret[0]).Type()
+ return Must(TryCreateList(s, t, ret))
}
func addCreateCtx(err error, s Scope) error {
return errors.WithContextf(err, "inserting Create in scope %s", s)
}
-// TryCreate inserts a fixed set of values into the pipeline. The values must
-// be of the same type.
+// TryCreate inserts a fixed non-empty set of values into the pipeline. The
+// values must be of the same type.
func TryCreate(s Scope, values ...interface{}) (PCollection, error) {
if len(values) == 0 {
return PCollection{}, addCreateCtx(errors.New("create has no
values"), s)
}
t := reflect.ValueOf(values[0]).Type()
+ return TryCreateList(s, t, values)
+}
+
+// TryCreateList inserts a fixed set of values into the pipeline from a slice
or
+// array. The values must be of the same type. Differently from TryCreate this
Review comment:
Same suggestion as above:
```suggestion
// array. The values must be of the same type. Unlike TryCreate this
```
##########
File path: sdks/go/pkg/beam/create.go
##########
@@ -34,31 +34,44 @@ func Create(s Scope, values ...interface{}) PCollection {
}
// CreateList inserts a fixed set of values into the pipeline from a slice or
-// array. It is a convenience wrapper over Create.
+// array. Differently from Create this supports the creation of an empty
Review comment:
Optional, but how about this wording?:
```suggestion
// array. Unlike Create this supports the creation of an empty
```
##########
File path: sdks/go/pkg/beam/create.go
##########
@@ -34,31 +34,44 @@ func Create(s Scope, values ...interface{}) PCollection {
}
// CreateList inserts a fixed set of values into the pipeline from a slice or
-// array. It is a convenience wrapper over Create.
+// array. Differently from Create this supports the creation of an empty
+// PCollection.
func CreateList(s Scope, list interface{}) PCollection {
- var ret []interface{}
val := reflect.ValueOf(list)
+ var ret []interface{}
+ for i := 0; i < val.Len(); i++ {
Review comment:
It seems better to have the error check below happen before this loop
(unless you have a specific reason for putting the loop first).
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