Defaulted .ToStringE to use reflection to find a stringer element

caste.go

@@ -119,6 +119,11 @@ func ToIntE(i interface{}) (int, error) {
 	}
 }
 
+var (
+	errorType       = reflect.TypeOf((*error)(nil)).Elem()
+	fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
+)
+
 func ToStringE(i interface{}) (string, error) {
 	jww.DEBUG.Println("ToStringE called on type:", reflect.TypeOf(i))
 
@@ -136,7 +141,12 @@ func ToStringE(i interface{}) (string, error) {
 	case nil:
 		return "", nil
 	default:
-		return "", fmt.Errorf("Unable to Cast %#v to string", i)
+		// shamelessly borrowed from html/template
+		v := reflect.ValueOf(i)
+		for !v.Type().Implements(fmtStringerType) && !v.Type().Implements(errorType) && v.Kind() == reflect.Ptr && !v.IsNil() {
+			v = v.Elem()
+		}
+		return fmt.Sprint(v), nil
 	}
 }