学习scala笔记--13 trait 调用链

 

 

 

 

 trait  调用链

 

 scala>  trait Logger { def log(log:String) {}}

defined trait Logger

 

scala>  trait aLogger extends Logger { override def log(log:String){println("---a---"+log); super.log(log)}}

defined trait aLogger

 

scala> trait bLogger extends Logger { override def log(log:String){println("---b---"+log); super.log(log)}}

defined trait bLogger

 

scala> trait cLogger extends Logger { override def log(log:String){println("---c---"+log); super.log(log)}}

defined trait cLogger

 

scala> class Person {

     |  def

     | 

     | }

<console>:4: error: identifier expected but '}' found.

       }

       ^

 

scala> class Person extends aLogger with bLogger with cLogger {

     |  def sayHello(name:String){

     |    println(" hello "+name)

     |    log(name)

     | }

     | }

defined class Person

 

scala> 

 

scala> var p = new Person

p: Person = Person@31c7c281

 

scala> p.sayHello("tomcat")

 hello tomcat

---c---tomcat

---b---tomcat

---a---tomcat