http: Make methods of .Data.Res actually work

http/handler.go

@@ -123,9 +123,13 @@ func (this *Handler) serveDocument (
 
 	// execute document
 	data := HTTPData { }
-	data.Res.Header      = recorder.Header()
-	data.Res.WriteHeader = recorder.WriteHeader
-	data.Res.Reset       = resetRecorder
+	data.Res = WrappedResponseWriter {
+		responseWriter: res,
+		resetFunc: resetRecorder,
+		Header: WrappedHeader {
+			Header: recorder.Header(),
+		},
+	}
 	data.Req = req
 	err = document.Execute(&recorder, step.ExecutionData {
 		Data: data,

http/http.go

@@ -8,15 +8,44 @@ import "net/http"
 // available to templates as they are being executed.
 type HTTPData struct {
 	// Res is like an http.ResponseWriter.
-	Res struct {
-		Header      http.Header
-		WriteHeader func (statusCode int)
-		Reset       func ()
-	}
+	Res WrappedResponseWriter
 	// Req is the HTTP request.
 	Req *http.Request
 }
 
+type WrappedResponseWriter struct {
+	responseWriter http.ResponseWriter
+	resetFunc func ()
+	Header WrappedHeader
+}
+
+func (this WrappedResponseWriter) WriteHeader (statusCode int) string {
+	this.responseWriter.WriteHeader(statusCode)
+	return ""
+}
+
+func (this WrappedResponseWriter) Reset () string {
+	this.resetFunc()
+	return ""
+}
+
+type WrappedHeader struct { http.Header }
+
+func (this WrappedHeader) Add (name, value string) string {
+	this.Header.Add(name, value)
+	return ""
+}
+
+func (this WrappedHeader) Del (name string) string {
+	this.Header.Del(name)
+	return ""
+}
+
+func (this WrappedHeader) Set (name, value string) string {
+	this.Header.Set(name, value)
+	return ""
+}
+
 var _ http.ResponseWriter = new(HTTPResponseRecorder)
 
 // HTTPResponseRecorder is an http.ResponseWriter that can buffer a response to