Merge b9b87f9c41 into f978e42036

structural/bridge.md

@@ -0,0 +1,62 @@
+# Bridge Pattern
+Decouples an interface from its implementation so that the two can vary independently
+
+## Implementation
+
+```go
+type Info struct {
+	Sender // who or which way to send information.        eg: QQ Wechat
+	MsgTag // the tag of msg.  just like log level tag.    eg: COMMON IMPORTANCE
+}
+
+func (i Info) Sending(to, msg string) {
+	msg = i.MsgTag(msg)
+	i.Sender.Send(to, msg)
+}
+
+// interface
+
+type Sender interface {
+	Send(to, msg string)
+}
+
+type MsgTag func(string) string
+
+
+// implementation
+
+type QQSender struct {
+}
+
+func (QQSender) Send(to, msg string) {
+	fmt.Println("[QQ] send to " + to + " with message: " + msg)
+}
+
+type WechatSender struct {
+}
+
+func (WechatSender) Send(to, msg string) {
+	fmt.Println("[Wechat] send to " + to + " with message: " + msg)
+}
+
+func ImportanceTag(msg string) string {
+	return "[IMPORTANCE] " + msg
+}
+
+func CommonTag(msg string) string {
+	return "[COMMON] " + msg
+}
+```
+
+## Usage
+```go
+info := &Info{MsgTag: ImportanceTag, Sender: QQSender{}}
+info.Sending("cbping", "hello world")
+
+info.Sender = WechatSender{}
+info.Sending("cbping", "hello world")
+
+info.MsgTag = CommonTag
+info.Sending("cbping", "hello world")
+```
+