convert multiple return values into a struct, add SelfLinker

pkg/api/latest/latest.go

@@ -49,16 +49,36 @@ var Codec = v1beta1.Codec
 // TODO: when versioning changes, make this part of each API definition.
 var ResourceVersioner = runtime.NewJSONBaseResourceVersioner()
 
+// SelfLinker can set or get the SelfLink field of all API types.
+// TODO: when versioning changes, make this part of each API definition.
+// TODO(lavalamp): Combine SelfLinker & ResourceVersioner interfaces, force all uses
+// to go through the InterfacesFor method below.
+var SelfLinker = runtime.NewJSONBaseSelfLinker()
+
+// VersionInterfaces contains the interfaces one should use for dealing with types of a particular version.
+type VersionInterfaces struct {
+	runtime.Codec
+	runtime.ResourceVersioner
+	runtime.SelfLinker
+}
+
 // InterfacesFor returns the default Codec and ResourceVersioner for a given version
 // string, or an error if the version is not known.
-func InterfacesFor(version string) (codec runtime.Codec, versioner runtime.ResourceVersioner, err error) {
+func InterfacesFor(version string) (*VersionInterfaces, error) {
 	switch version {
 	case "v1beta1":
-		codec, versioner = v1beta1.Codec, ResourceVersioner
+		return &VersionInterfaces{
+			Codec:             v1beta1.Codec,
+			ResourceVersioner: ResourceVersioner,
+			SelfLinker:        SelfLinker,
+		}, nil
 	case "v1beta2":
-		codec, versioner = v1beta2.Codec, ResourceVersioner
+		return &VersionInterfaces{
+			Codec:             v1beta2.Codec,
+			ResourceVersioner: ResourceVersioner,
+			SelfLinker:        SelfLinker,
+		}, nil
 	default:
-		err = fmt.Errorf("unsupported storage version: %s (valid: %s)", version, strings.Join(Versions, ", "))
+		return nil, fmt.Errorf("unsupported storage version: %s (valid: %s)", version, strings.Join(Versions, ", "))
 	}
-	return
 }

pkg/api/latest/latest_test.go

@@ -146,11 +146,11 @@ func TestCodec(t *testing.T) {
 }
 
 func TestInterfacesFor(t *testing.T) {
-	if _, _, err := InterfacesFor(""); err == nil {
+	if _, err := InterfacesFor(""); err == nil {
 		t.Fatalf("unexpected non-error: %v", err)
 	}
 	for i, version := range append([]string{Version, OldestVersion}, Versions...) {
-		if codec, versioner, err := InterfacesFor(version); err != nil || codec == nil || versioner == nil {
+		if vi, err := InterfacesFor(version); err != nil || vi == nil {
 			t.Fatalf("%d: unexpected result: %v", i, err)
 		}
 	}

pkg/client/client.go

@@ -108,12 +108,12 @@ func New(host, version string, auth *AuthInfo) (*Client, error) {
 		// TODO: implement version negotation (highest version supported by server)
 		version = latest.Version
 	}
-	serverCodec, _, err := latest.InterfacesFor(version)
+	versionInterfaces, err := latest.InterfacesFor(version)
 	if err != nil {
 		return nil, fmt.Errorf("API version '%s' is not recognized (valid values: %s)", version, strings.Join(latest.Versions, ", "))
 	}
 	prefix := fmt.Sprintf("/api/%s/", version)
-	restClient, err := NewRESTClient(host, auth, prefix, serverCodec)
+	restClient, err := NewRESTClient(host, auth, prefix, versionInterfaces.Codec)
 	if err != nil {
 		return nil, fmt.Errorf("API URL '%s' is not valid: %v", host, err)
 	}

pkg/master/master.go

@@ -73,11 +73,11 @@ func NewEtcdHelper(etcdServers []string, version string) (helper tools.EtcdHelpe
 	if version == "" {
 		version = latest.Version
 	}
-	codec, versioner, err := latest.InterfacesFor(version)
+	versionInterfaces, err := latest.InterfacesFor(version)
 	if err != nil {
 		return helper, err
 	}
-	return tools.EtcdHelper{client, codec, versioner}, nil
+	return tools.EtcdHelper{client, versionInterfaces.Codec, versionInterfaces.ResourceVersioner}, nil
 }
 
 // New returns a new instance of Master connected to the given etcd server.