Question

对于那些需要上下文的人，我正在研究Python Crash课程，第176页。对于最后一行代码，为什么我可以在my_tesla.battery.describe_battery()之前键入self.而没有battery？

class Car():

  def __init__(self,make,model,year):
    self.make = make
    self.model = model
    self.year = year
    self.odometer = 20000

  def get_description(self):
    """This function gives a full name of the cars make, model and year and returns it to the function."""
    long_name = str(self.year) + " " + self.make + " " + self.model
    return long_name.title()

  def odometer_reading(self):
    """This function prints the odometer reading of the vehicle."""
    return self.odometer

  def update_mileage(self, mileage):
    if mileage >= self.odometer:
      self.odometer = mileage
    else:
      print("You can not roll back the odometer!")  


  def increase_mileage(self, mile):
    self.odometer += mile
    return self.odometer



class Battery():

  """This creates the classes __init__ method and sets a default battery_size to 70"""
  def __init__(self,battery_size=70):
    self.battery_size = battery_size

  def describe_battery(self):
      print("This car has a " + str(self.battery_size) + "-kWh battery.")



class ElectricCar(Car):
  """Initializes the parents class - Car() into the child class - ElectricCar()."""
  def __init__(self,make,model,year):
    super().__init__(make,model,year)
    self.battery = Battery()




my_tesla=ElectricCar('tesla','model s', 2016)
print(my_tesla.get_description())
my_tesla.battery.describe_battery()`

我希望输入：

my_tesla.self.battery.describe_battery()，以允许使用属性battery。

为什么我不必使用自我。在另一个类创建的属性前面？

0 个答案: