Use a stronger type for []stats.Measurement in Record

stats/internal/record.go

@@ -15,11 +15,9 @@
 package internal
 
 import (
+	"go.opencensus.io/stats"
 	"go.opencensus.io/tag"
 )
 
-// DefaultRecorder will be called for each Record call.
-var DefaultRecorder func(tags *tag.Map, measurement interface{}, attachments map[string]interface{})
-
 // SubscriptionReporter reports when a view subscribed with a measure.
 var SubscriptionReporter func(measure string)

stats/record.go

@@ -31,12 +31,15 @@ func init() {
 	}
 }
 
+// DefaultRecorder will be called for each Record call.
+var DefaultRecorder func(tags *tag.Map, measurement []Measurement, attachments map[string]interface{})
+
 // Recorder provides an interface for exporting measurement information from
 // the static Record method by using the WithRecorder option.
 type Recorder interface {
 	// Record records a set of measurements associated with the given tags and attachments.
 	// The second argument is a `[]Measurement`.
-	Record(*tag.Map, interface{}, map[string]interface{})
+	Record(*tag.Map, []Measurement, map[string]interface{})
 }
 
 type recordOptions struct {
@@ -109,7 +112,7 @@ func RecordWithOptions(ctx context.Context, ros ...Options) error {
 	if len(o.measurements) == 0 {
 		return nil
 	}
-	recorder := internal.DefaultRecorder
+	recorder := DefaultRecorder
 	if o.recorder != nil {
 		recorder = o.recorder.Record
 	}

stats/view/worker.go

@@ -23,14 +23,13 @@ import (
 	"go.opencensus.io/metric/metricdata"
 	"go.opencensus.io/metric/metricproducer"
 	"go.opencensus.io/stats"
-	"go.opencensus.io/stats/internal"
 	"go.opencensus.io/tag"
 )
 
 func init() {
 	defaultWorker = NewMeter().(*worker)
 	go defaultWorker.start()
-	internal.DefaultRecorder = record
+	stats.DefaultRecorder = record
 }
 
 type measureRef struct {
@@ -188,15 +187,15 @@ func (w *worker) RetrieveData(viewName string) ([]*Row, error) {
 	return resp.rows, resp.err
 }
 
-func record(tags *tag.Map, ms interface{}, attachments map[string]interface{}) {
+func record(tags *tag.Map, ms []stats.Measurement, attachments map[string]interface{}) {
 	defaultWorker.Record(tags, ms, attachments)
 }
 
 // Record records a set of measurements ms associated with the given tags and attachments.
-func (w *worker) Record(tags *tag.Map, ms interface{}, attachments map[string]interface{}) {
+func (w *worker) Record(tags *tag.Map, ms []stats.Measurement, attachments map[string]interface{}) {
 	req := &recordReq{
 		tm:          tags,
-		ms:          ms.([]stats.Measurement),
+		ms:          ms,
 		attachments: attachments,
 		t:           time.Now(),
 	}