mirror of
https://github.com/crazybber/awesome-patterns.git
synced 2024-11-22 20:56:02 +03:00
111 lines
2.5 KiB
Go
111 lines
2.5 KiB
Go
// 访问者模式 visitor pattern.
|
||
// 该模式用于将数据结构和操作进行分离，同样用于分离操作的还有策略模式(strategy pattern)，但两者存在侧重点的不同.
|
||
// 访问者模式侧重于扩展访问的方法类型，是为了对某一个类及其子类的访问方式进行扩展，允许增加更多不同的访问者，但不宜增加更多的Host.
|
||
// 以下以实体A(仅有玩家、NPC、物体三类)被访问(查看信息、发起挑战等，此处可扩展)的过程
|
||
package main
|
||
|
||
import "log"
|
||
|
||
// 如果这里有更多的新类型Host需要扩展，则不宜使用访问者模式
|
||
type Host interface {
|
||
Accept(Visitor)
|
||
}
|
||
|
||
type PlayerHost struct {
|
||
Name string
|
||
Level int
|
||
}
|
||
|
||
func (p PlayerHost)Accept(v Visitor){
|
||
v.VisitPlayer(p)
|
||
}
|
||
|
||
type NPCHost struct {
|
||
Name string
|
||
IsImmortal bool
|
||
}
|
||
|
||
func (n NPCHost)Accept(v Visitor){
|
||
v.VisitNPC(n)
|
||
}
|
||
|
||
type ObjectHost struct {
|
||
Name string
|
||
Price int
|
||
}
|
||
|
||
func (o ObjectHost)Accept(v Visitor){
|
||
v.VisitObject(o)
|
||
}
|
||
|
||
type Visitor interface {
|
||
VisitPlayer(PlayerHost)
|
||
VisitNPC(NPCHost)
|
||
VisitObject(ObjectHost)
|
||
}
|
||
|
||
// 访问者允许有不同类型的访问者
|
||
// 仅查看信息的访问者
|
||
type InfoVisitor struct {}
|
||
|
||
func (InfoVisitor) VisitPlayer(p PlayerHost) {
|
||
log.Printf("Player -> Name:%s ,Level:%d\n" ,p.Name ,p.Level)
|
||
}
|
||
|
||
func (InfoVisitor) VisitNPC(n NPCHost) {
|
||
log.Printf("NPC -> Name:%s ,Immortal:%v\n" ,n.Name ,n.IsImmortal)
|
||
}
|
||
|
||
func (InfoVisitor) VisitObject(o ObjectHost) {
|
||
log.Printf("Object -> Name:%s ,Price:%d\n" ,o.Name ,o.Price)
|
||
}
|
||
|
||
// 发起攻击的访问者
|
||
type AggressiveVisitor struct {}
|
||
|
||
func (AggressiveVisitor) VisitPlayer(p PlayerHost) {
|
||
log.Printf("Attack %s\n" ,p.Name)
|
||
}
|
||
|
||
func (AggressiveVisitor) VisitNPC(n NPCHost) {
|
||
log.Printf("Attack NPC %s\n" ,n.Name)
|
||
}
|
||
|
||
func (AggressiveVisitor) VisitObject(o ObjectHost) {
|
||
log.Printf("Unsupported target %s\n" ,o.Name)
|
||
}
|
||
|
||
func main(){
|
||
infoVst := InfoVisitor{}
|
||
agrVst := AggressiveVisitor{}
|
||
|
||
pA := PlayerHost{"icg" ,1}
|
||
pB := PlayerHost{"sz" ,2}
|
||
npc := NPCHost{"nyn" ,true}
|
||
obj := ObjectHost{"cake" ,19}
|
||
|
||
hostList := []Host{pA ,npc ,obj ,pB}
|
||
|
||
for _ ,v := range hostList{
|
||
v.Accept(infoVst)
|
||
}
|
||
println()
|
||
for _ ,v := range hostList{
|
||
v.Accept(agrVst)
|
||
}
|
||
/*
|
||
output:
|
||
2019/05/04 10:00:49 Player -> Name:icg ,Level:1
|
||
2019/05/04 10:00:49 NPC -> Name:nyn ,Immortal:true
|
||
2019/05/04 10:00:49 Object -> Name:cake ,Price:19
|
||
2019/05/04 10:00:49 Player -> Name:sz ,Level:2
|
||
|
||
2019/05/04 10:00:49 Attack icg
|
||
2019/05/04 10:00:49 Attack NPC nyn
|
||
2019/05/04 10:00:49 Unsupported target cake
|
||
2019/05/04 10:00:49 Attack sz
|
||
*/
|
||
|
||
}
|
||
|