语言真正是想通的，写swift让我想到了js和java

//
//  main.swift
//  StudyVarsAndConstants
//
//  Created by UPMI_iMac01 on 15/9/19.
//  Copyright © 2015年 upmi. All rights reserved.
//

import Foundation


class Student{
    func sayHi()
    {
        
    }
    
}

class Persion:Student{
    
    var _name:String
    
    init(name:String) {
        self._name = name
    }
    
    override func sayHi() {
        print("say \(self._name)")
    }
}

var student = Student()
student.sayHi()

var persion = Persion(name: "yihong")
persion.sayHi()