Python - 覆盖父类参数

Question

我有一个超类和一个子类。

class Vehicle:
   def __init__(self, new_fuel, new_position):
        self.fuel = new_fuel
        self.position = new_position

class Car(Vehicle):
   # Here, I am stating that when Car is initialized, the position will be 
   # at (0, 0), so when you call it, you do not have to give it a new_position argument 
    def __init__(self, new_fuel, new_position=(0, 0)):
        super(Car, self).__init__(new_fuel, new_position)
        self.new_position = new_position

问题：

我希望它用 10 个燃料和 (0, 0) 的位置初始化一个 Car 对象，但我不想为 new_position 设置参数，因为我已经说过，当所有汽车都初始化时，它们的位置为 ( 0, 0)。 另外，我不想更改父类（车辆）中的任何参数，我只想在子类（例如 Car）中覆盖它们。

test_car = Car(10)
print(test_car.new_position)
>>> (0,0)

但是，它不断给我这个错误，并要求为 new_position 提供一个参数

TypeError: __init__() missing 1 required positional argument: 'new_position'

Answer 1

据我了解您要实现的目标，只需从 Car __init__ 方法中删除“new_position”参数即可。

class Vehicle:
   def __init__(self, new_fuel, new_position):
        self.fuel = new_fuel
        self.position = new_position

class Car(Vehicle):
   # Here, I am stating that when Car is initialized, the position will be 
   # at (0, 0), so when you call it, you do not have to give it a new_position argument 
    def __init__(self, new_fuel):
        super(Car, self).__init__(new_fuel, new_position= (0, 0))

稍后当 Car 类中的任何方法需要一个“位置”参数时，它会在 Car 类中搜索，如果找不到，它会跳到 Vehicle 并找到它。

假设您已经在 Vehicle 类中实现了 get_position() 方法。

class Vehicle:
    <everything as always>

    def get_position(self):
        return self.position

class Car(Vehicle):
   <everything as always>

a = Car(10)
a.get_position() # Returns (0, 0)

编辑评论：

class Vehicle:
    def __init__(self, new_fuel):
        self.fuel = new_fuel

    def get_position(self):
        return self.__class__.POSITION

class Car(Vehicle):
    POSITION = (0, 0)
    # Here, I am stating that when Car is initialized, the position will be 
    # at (0, 0), so when you call it, you do not have to give it a new_position argument 
    def __init__(self, new_fuel):
       super(Car, self).__init__(new_fuel)

    def new_position(self, value):
       self.__class__.POSITION = value

a = Car(10)
b = Car(20)
c = Car(30)

for each in [a, b, c]:
    print(each.get_position())
(0, 0)
(0, 0)
(0, 0)
c.new_position((0, 1))
for each in [a, b, c]:
    print(each.get_position()) 
(0, 1)
(0, 1)
(0, 1)