Implement pflag slice value interface for image types

cmd/skaffold/app/flags/image.go

@@ -36,23 +36,18 @@ type image struct {
 	artifact *build.Artifact
 }
 
-// String Implements String() method for pflag interface and
-// returns a comma separated list of images.
-func (i *Images) String() string {
+// GetSlice Implements GetSlice() method for pflag SliceValue interface and
+// returns a slice image names.
+func (i *Images) GetSlice() []string {
 	names := make([]string, len(i.images))
 	for i, image := range i.images {
 		names[i] = image.name
 	}
-	return strings.Join(names, ",")
+	return names
 }
 
-// Usage Implements Usage() method for pflag interface
-func (i *Images) Usage() string {
-	return i.usage
-}
-
-// Set Implements Set() method for pflag interface
-func (i *Images) Set(value string) error {
+// Append Implements Append() method for pflag SliceValue interface
+func (i *Images) Append(value string) error {
 	a, err := convertImageToArtifact(value)
 	if err != nil {
 		return err
@@ -61,9 +56,18 @@ func (i *Images) Set(value string) error {
 	return nil
 }
 
-// Type Implements Type() method for pflag interface
-func (i *Images) Type() string {
-	return fmt.Sprintf("%T", i)
+// Replace Implements Replace() method for pflag SliceValue interface
+func (i *Images) Replace(images []string) error {
+	newImages := make([]image, len(i.images))
+	for _, value := range images {
+		a, err := convertImageToArtifact(value)
+		if err != nil {
+			return err
+		}
+		newImages = append(newImages, image{name:value, artifact:a})
+		i.images = newImages
+	}
+	return nil
 }
 
 // Artifacts returns an artifact representation for the corresponding image