From 7ebab7875bde8c99c091e85808bc9ee5a89fa317 Mon Sep 17 00:00:00 2001
From: Zachary Schulze <zach.schulze@uber.com>
Date: Fri, 23 Jul 2021 11:39:30 -0700
Subject: [PATCH] update

- Added AddHelperFunction comment/usage
- AddHelperFunction returns err on duplicate key definitions
---
 v2/pkg/operators/common/dsl/dsl.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/v2/pkg/operators/common/dsl/dsl.go b/v2/pkg/operators/common/dsl/dsl.go
index ea8a97b93..37820b9a9 100644
--- a/v2/pkg/operators/common/dsl/dsl.go
+++ b/v2/pkg/operators/common/dsl/dsl.go
@@ -7,6 +7,7 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"html"
 	"math"
@@ -234,15 +235,18 @@ var functions = map[string]govaluate.ExpressionFunction{
 	},
 }
 
-// HelperFunctions contains the dsl helper functions
+// HelperFunctions returns the dsl helper functions
 func HelperFunctions() map[string]govaluate.ExpressionFunction {
 	return functions
 }
 
-func AddHelperFunction(key string, value func(args ...interface{}) (interface{}, error)) {
+// AddHelperFunction allows creation of additiona helper functions to be supported with templates
+func AddHelperFunction(key string, value func(args ...interface{}) (interface{}, error)) error {
 	if _, ok := functions[key]; !ok {
 		functions[key] = value
+		return nil
 	}
+	return errors.New("duplicate helper function key defined")
 }
 
 func reverseString(s string) string {