use type switch with var assignment

quasilyte · quasilyte · commit 8182ba6c11d5 · 2018-07-28T17:23:16.000+03:00
This makes it possible to avoid redundant type assertions. Found with https://go-critic.github.io/overview#typeswitchvar
diff --git a/sqlx.go b/sqlx.go
@@ -149,15 +149,15 @@ func isUnsafe(i interface{}) bool {
 }
 
 func mapperFor(i interface{}) *reflectx.Mapper {
-	switch i.(type) {
+	switch i := i.(type) {
 	case DB:
-		return i.(DB).Mapper
+		return i.Mapper
 	case *DB:
-		return i.(*DB).Mapper
+		return i.Mapper
 	case Tx:
-		return i.(Tx).Mapper
+		return i.Mapper
 	case *Tx:
-		return i.(*Tx).Mapper
+		return i.Mapper
 	default:
 		return mapper()
 	}
diff --git a/types/types.go b/types/types.go
@@ -30,11 +30,11 @@ func (g GzippedText) Value() (driver.Value, error) {
 // the wire and storing the raw result in the GzippedText.
 func (g *GzippedText) Scan(src interface{}) error {
 	var source []byte
-	switch src.(type) {
+	switch src := src.(type) {
 	case string:
-		source = []byte(src.(string))
+		source = []byte(src)
 	case []byte:
-		source = src.([]byte)
+		source = src
 	default:
 		return errors.New("Incompatible type for GzippedText")
 	}
