make all kubectl config set-* easier to use

pkg/util/string_flag.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import ()
+
+// StringFlag is a string flag compatible with flags and pflags that keeps track of whether it had a value supplied or not.
+type StringFlag struct {
+	// If Set has been invoked this value is true
+	provided bool
+	// The exact value provided on the flag
+	value string
+}
+
+func (f *StringFlag) Default(value string) {
+	f.value = value
+}
+
+func (f StringFlag) String() string {
+	return f.value
+}
+
+func (f StringFlag) Value() string {
+	return f.value
+}
+
+func (f *StringFlag) Set(value string) error {
+	f.value = value
+	f.provided = true
+
+	return nil
+}
+
+func (f StringFlag) Provided() bool {
+	return f.provided
+}
+
+func (f *StringFlag) Type() string {
+	return "string"
+}