Use GetSlice and get/set by string pointer.

merge after

Author: yuwenma

examples/set-labels-imperative/.expected/diff.patch

@@ -1,24 +1,19 @@
 diff --git a/app.yaml b/app.yaml
-index 1e641f7..bb4be90 100644
+index d67a0d2..bf55161 100644
 --- a/app.yaml
 +++ b/app.yaml
-@@ -2,6 +2,9 @@ apiVersion: v1
- kind: ConfigMap
- metadata:
-   name: the-map
-+  labels:
-+    color: orange
-+    fruit: apple
- data:
-   some-key: some-value
- ---
-@@ -10,6 +13,9 @@ kind: MyResource
+@@ -9,7 +9,7 @@ apiVersion: v1
+ kind: Service
  metadata:
    name: the-service
-   namespace: the-namespace
-+  labels:
-+    color: orange
-+    fruit: apple
+-  namespace: example
++  namespace: new-ns
  spec:
-   selector:
-     labels:
+   ports:
+     - name: etcd-server-ssl
+@@ -34,4 +34,4 @@ spec:
+ apiVersion: v1
+ kind: Namespace
+ metadata:
+-  name: example
++  name: new-ns

examples/set-namespace-imperative/.expected/config.yaml

@@ -1,4 +1,4 @@
 testType: eval
 image: gcr.io/kpt-fn/set-namespace:unstable
 args:
-  namespace: example-ns
+  namespace: new-ns

examples/set-namespace-imperative/.expected/diff.patch

@@ -1,19 +1,19 @@
 diff --git a/app.yaml b/app.yaml
-index 1f8aeee..33e42da 100644
+index d67a0d2..bf55161 100644
 --- a/app.yaml
 +++ b/app.yaml
 @@ -9,7 +9,7 @@ apiVersion: v1
  kind: Service
  metadata:
    name: the-service
--  namespace: the-namespace
-+  namespace: example-ns
+-  namespace: example
++  namespace: new-ns
  spec:
    ports:
      - name: etcd-server-ssl
-@@ -21,4 +21,4 @@ spec:
+@@ -34,4 +34,4 @@ spec:
  apiVersion: v1
  kind: Namespace
  metadata:
 -  name: example
-+  name: example-ns
++  name: new-ns

examples/set-namespace-imperative/README.md

@@ -2,9 +2,9 @@
 
 ### Overview
 
-This examples shows how to set namespace in the `.metadata.namespace` field on
-all resources by running [`set-namespace`] function imperatively. Resources that
-are known to be cluster-scoped will be skipped.
+This examples shows how to replace KRM resources' namespace fields by matching
+the namespace with the namespace object's `metadata.name`.  
+The example uses `kpt fn eval` to run the function imperatively.
 
 ### Fetch the example package
 
@@ -27,6 +27,7 @@ The desired namespace is provided after `--` and it will be converted to
 
 ### Expected result
 
-Check all resources have `metadata.namespace` set to `example-ns`:
+Only the namespace fields which match the `namespace` "example" object has the value updated to
+`new-ns`:
 
 [`set-namespace`]: https://catalog.kpt.dev/set-namespace/v0.1/

examples/set-namespace-imperative/app.yaml

@@ -9,7 +9,20 @@ apiVersion: v1
 kind: Service
 metadata:
   name: the-service
-  namespace: the-namespace
+  namespace: example
+spec:
+  ports:
+    - name: etcd-server-ssl
+      port: 2380
+    - name: etcd-client-ssl
+      port: 2379
+  publishNotReadyAddresses: true
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: the-service
+  namespace: not-match-example
 spec:
   ports:
     - name: etcd-server-ssl

functions/go/set-namespace/Dockerfile

@@ -3,30 +3,34 @@ module github.com/GoogleContainerTools/kpt-functions-catalog/functions/go/set-na
 go 1.17
 
 require (
-	github.com/GoogleContainerTools/kpt-functions-sdk/go/fn v0.0.0-20220326221816-442298f7a17c
+	github.com/GoogleContainerTools/kpt-functions-sdk/go/fn v0.0.0-20220405020624-e5817d5d2014
 	k8s.io/apimachinery v0.23.5
 )
 
 require (
 	github.com/PuerkitoBio/purell v1.1.1 // indirect
 	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/go-errors/errors v1.0.1 // indirect
-	github.com/go-logr/logr v1.2.0 // indirect
+	github.com/go-errors/errors v1.4.2 // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
 	github.com/go-openapi/jsonpointer v0.19.5 // indirect
-	github.com/go-openapi/jsonreference v0.19.3 // indirect
-	github.com/go-openapi/swag v0.19.5 // indirect
-	github.com/mailru/easyjson v0.7.0 // indirect
+	github.com/go-openapi/jsonreference v0.19.6 // indirect
+	github.com/go-openapi/swag v0.21.1 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/google/gnostic v0.6.7 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/stretchr/testify v1.7.0 // indirect
-	github.com/xlab/treeprint v0.0.0-20181112141820-a009c3971eca // indirect
-	golang.org/x/net v0.0.0-20211209124913-491a49abca63 // indirect
+	github.com/stretchr/testify v1.7.1 // indirect
+	github.com/xlab/treeprint v1.1.0 // indirect
+	golang.org/x/net v0.0.0-20220403103023-749bd193bc2b // indirect
 	golang.org/x/text v0.3.7 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
-	k8s.io/klog/v2 v2.30.0 // indirect
-	k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65 // indirect
-	sigs.k8s.io/kustomize/kyaml v0.13.3 // indirect
+	k8s.io/klog/v2 v2.60.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20220401212409-b28bf2818661 // indirect
+	sigs.k8s.io/kustomize/kyaml v0.13.6 // indirect
 )