improved message building

README.md

@@ -71,7 +71,7 @@ A processor works like a middleware, in fact forwards messages only if the predi
 ```go
 
 eventbus.Channel("topic1").Processor(func(message goeventbus.Message) bool {
-	return logic
+	return message.
 })
 ```
 

channel_test.go

@@ -72,11 +72,13 @@ func TestMessageOptions(t *testing.T) {
 
 	wg.Add(1)
 	eventBus.Channel("address").Subscriber().Listen(func(context Context) {
-		assert.Equal(t, "value", context.Result().Options.Header("key"))
+		assert.True(t, context.Result().Options.Headers().Contains("key"))
+		assert.Equal(t, "value", context.Result().Options.Headers().Header("key"))
 		wg.Done()
 	})
 
-	message := CreateMessage().SetBody("Hi There").SetOptions(NewMessageOptions().AddHeader("key", "value"))
+	options := NewMessageOptions().SetHeaders(NewHeaders().Add("key", "value"))
+	message := CreateMessage().SetBody("Hi There").SetOptions(options)
 	eventBus.Channel("address").Publisher().Publish(message)
 	wg.Wait()
 }

examples/main.go

@@ -44,7 +44,8 @@ func main() {
 }
 
 func publishTo(address string, data string) {
-	options := goeventbus.NewMessageOptions().AddHeader("header", "value")
+
+	options := goeventbus.NewMessageOptions().SetHeaders(goeventbus.NewHeaders().Add("header", "value"))
 	message := goeventbus.CreateMessage().SetBody(data).SetOptions(options)
 	for {
 		eventbus.Channel(address).Publisher().Publish(message)

message_options.go

@@ -1,25 +1,42 @@
 package goeventbus
 
 type MessageOptions struct {
-	headers map[string]string
-}
-
-func (op MessageOptions) AddHeader(key string, value string) MessageOptions {
-	op.headers[key] = value
-	return op
+	headers Headers
 }
 
-func (op MessageOptions) SetHeader(headers map[string]string) MessageOptions {
+func (op MessageOptions) SetHeaders(headers Headers) MessageOptions {
 	op.headers = headers
 	return op
 }
 
-func (op MessageOptions) Header(key string) string {
-	return op.headers[key]
+func (op MessageOptions) Headers() Headers {
+	return op.headers
 }
 
 func NewMessageOptions() MessageOptions {
 	return MessageOptions{
-		headers: map[string]string{},
+		headers: Headers{},
 	}
 }
+
+type Headers struct {
+	headers map[string]string
+}
+
+func (h Headers) Add(key string, value string) Headers {
+	h.headers[key] = value
+	return h
+}
+
+func (h Headers) Header(key string) string {
+	return h.headers[key]
+}
+
+func (h Headers) Contains(key string) bool {
+	_, exist := h.headers[key]
+	return exist
+}
+
+func NewHeaders() Headers {
+	return Headers{}
+}