redesign the header API

I'm quite satisfied with this right now (though this doesn't say
anything about how I feel about it tomorrow), but it's ugly that some
guts (headers.Base) are exposed in the public API.

1 files changed, 52 insertions, 0 deletions

diff --git a/headers/metadata.go b/headers/metadata.go
new file mode 100644
index 0000000..8f07e89
--- /dev/null
+++ b/headers/metadata.go
@@ -0,0 +1,52 @@
+/******************************************************************************
+*
+*  Copyright 2018 Stefan Majewsky <majewsky@gmx.net>
+*
+*  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 headers
+
+//Metadata is a helper type that provides safe access to the metadata headers
+//in a schwift.Headers instance. It cannot be directly constructed, but each
+//subtype of schwift.Headers has a field "Metadata" of this type. For example:
+//
+//    var hdr ObjectHeaders
+//    //the following two statements are equivalent
+//    hdr.Set("X-Object-Meta-Access", "strictly confidential")
+//    hdr.Metadata.Set("Access", "strictly confidential")
+//    //because hdr.Metadata is a headers.Metadata instance
+type Metadata struct {
+	Base
+}
+
+//Clear works like Headers.Clear(), but prepends the metadata prefix to the key.
+func (m Metadata) Clear(key string) {
+	m.H.Clear(m.K + key)
+}
+
+//Del works like Headers.Del(), but prepends the metadata prefix to the key.
+func (m Metadata) Del(key string) {
+	m.H.Del(m.K + key)
+}
+
+//Get works like Headers.Get(), but prepends the metadata prefix to the key.
+func (m Metadata) Get(key string) string {
+	return m.H.Get(m.K + key)
+}
+
+//Set works like Headers.Set(), but prepends the metadata prefix to the key.
+func (m Metadata) Set(key, value string) {
+	m.H.Set(m.K+key, value)
+}