python基础知识（继承）

继承的基本语法

class  Class(继承那个基类如果有多个基类用逗号隔开，如果没有就继承object):

　　""" 类的帮助信息"""

　　类体

方法重写

派生类中调用基类的__init__()方法

 

方法重写

在派生类中重写方法

 

在派生类中调用基类的__init__()方法

super()可以在派生类当中调用基类的构造方法

 

例

class Car():
  """一次模拟汽车的简单尝试"""
  def __init__(self, make, model, year):
    self.make = make
    self.model = model
    self.year = year
    self.odometer_reading = 0
    
  def get_descriptive_name(self):
    long_name = str(self.year) + ' ' + self.make + ' ' + self.model
    return long_name.title()
 
  def read_odometer(self):
    print("This car has " + str(self.odometer_reading) + " miles on it.")
    
  def update_odometer(self, mileage):
    if mileage >= self.odometer_reading:
      self.odometer_reading = mileage
    else:
      print("You can't roll back an odometer!")
      
  def increment_odometer(self, miles):
    self.odometer_reading += miles

class Battery():

  def __init__(self, battery_size = 70):
    self.battery_size = battery_size

  def print_battery(self):
    print(self.battery_size)

  def get_range(self):
    """打印一条消息，指出电瓶的续航里程"""
    if self.battery_size == 70:
      range = 240
    elif self.battery_size == 85:
      range = 270
    message = "This car can go approximately " + str(range)
    message += " miles on a full charge."
    print(message)

  def upgrade_battery(self):
    if self.battery_size != 85:
      self.battery_size = 85
    print(self.battery_size)

class ElectricCar(Car):
      #电动汽车的独特之处
    def __init__(self, make, model, year):
      #初始化父类的属性
      super().__init__(make, model, year)
      self.battery =Battery()
          
my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.battery.upgrade_battery()
my_tesla.battery.print_battery()
my = ElectricCar('tesla', 'model s', 2017)
my.battery.get_range()
my.battery.upgrade_battery()
my.battery.get_range()