最近在加强JAVA和Python，今天刚看了Python中类的定义，与其他的都不同，做一下笔记

PHP:
class A entends B {
      public $a;
      public function __construct($a){
            $this->a=$a;
      }
}
调用时$a = new A(x)

JAVA:
class A entends B {
      private int a;
      A(int x){
            this.a = x;
      }
调用时A a = new A(2);

Python:
class Student(object):
      def __init__(self,name,age):
            self.__name = name
            self.__age = age
      def outp(self):
            print(self.__name)
            print(self.__age)
Goodstudent(Student):
      def __init__(self,name):
            self.__name = name
            self.__age = 99
调用时a = Goodstudent("tom")
a.outp()