youngoli commented on a change in pull request #10991: [BEAM-3301] Refactor
DoFn validation & allow specifying main inputs.
URL: https://github.com/apache/beam/pull/10991#discussion_r388089313
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File path: sdks/go/pkg/beam/core/graph/fn.go
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@@ -209,21 +209,58 @@ func (f *DoFn) RestrictionT() *reflect.Type {
// a KV or not based on the other signatures (unless we're more loose about
which
// sideinputs are present). Bind should respect that.
+// Constants so we can avoid magic numbers in validation. Represent number of
+// DoFn main inputs based on what kind of input the DoFn has.
+const (
+ unknownInNum = -1 // Used when we don't know the number of main inputs.
+ singleInNum = 1
+ kvInNum = 2
+)
+
// NewDoFn constructs a DoFn from the given value, if possible.
func NewDoFn(fn interface{}) (*DoFn, error) {
ret, err := NewFn(fn)
if err != nil {
return nil, errors.WithContext(errors.Wrapf(err, "invalid
DoFn"), "constructing DoFn")
}
- return AsDoFn(ret)
+ return AsDoFn(ret, unknownInNum)
}
-// AsDoFn converts a Fn to a DoFn, if possible.
-func AsDoFn(fn *Fn) (*DoFn, error) {
+// NewDoFnKv constructs a DoFn from the given value, if possible, with
+// improved validation from knowing whether the DoFn's main input is a KV or
+// single element.
+func NewDoFnKv(fn interface{}, mainKv bool) (*DoFn, error) {
Review comment:
Done, went with the variadic options made of functions approach. If anyone
else is reading this, based it off this article:
https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis
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