学习scala笔记--27 类型参数--视图边界

 

 

 

视图边界

 

 

scala> class Person(val name:String){

     |  def sayHello= println(" hello i'm "+name)

     |  def makeFriends(p :Person) {

     |      sayHello 

     |      p.sayHello

     |  }

     | }

defined class Person

 

scala> 

 

scala> class Student(name:String) extends Person(name)

defined class Student

 

scala> class Dog(val name:String) { def sayHello = println(" wang wnag i'm "+name)}

defined class Dog

 

 

-- 注意这里隐式类型转换

scala> implicit  def dog2person(dog:Object):Person = if( dog.isInstanceOf[Dog]) { val _dog = asInstanceOf[Dog] ;new Person(_dog.name)} else Nil

 

 

 scala> class party[T  <% Person](p1 :T , p2 :T)

defined class party

 

scala> 

 

scala> val d = new Dog("dog")

d: Dog = Dog@a4388f1

 

scala> val s = new Student("std")

s: Student = Student@735dc133

 

scala> val pt = new party(d,s)

pt: party[Object] = party@1b5df8b7