我们可以传递给 super() 什么参数? [英] What argument can we pass to super()?

问题描述

我创建了一个 Vehicle 类，并希望从它派生一个 Car 类，它调用父构造函数来设置 name 和 <代码>颜色.但是我收到此错误:

I created a Vehicle class and want to also have a Car class derived from it that calls the parent constructor to set name and color. However I'm getting this error:

super() takes at least 1 argument (0 given)

这是我的代码:

class Vehicle:

    def __init__(self, name, color):
        self.__name = name      # __name is private to Vehicle class
        self.__color = color

    def getColor(self):         # getColor() function is accessible to class Car
        return self.__color

    def setColor(self, color):  # setColor is accessible outside the class
        self.__color = color

    def getName(self):          # getName() is accessible outside the class
        return self.__name
        self.__model = model

    def getDescription(self):
        return self.getName() + self.__model + " in " + self.getColor() + " color"


class Car(Vehicle):

    def __init__(self, name, color, model):
        # call parent constructor to set name and color
        super().__init__(name,  color)
        self.__model = model

    def getDescription(self):
        return self.getName() + self.__model + " in " + self.getColor() + " color"

# in method getDescrition we are able to call getName(), getColor() because they are
# accessible to child class through inheritance

c = Car("Ford Mustang", "red", "GT350")
print(c.getDescription())

推荐答案

Python 3 - nice

在 Python 3 中这是有效的:

Python 3 - nice

In Python 3 this works:

class Vehicle:
    def __init__(self):
        print('Vehicle __init__() called')

class Car(Vehicle):
    def __init__(self):
        super().__init__()

car = Car()

印刷品:

Vehicle __init__() called

Python 2 - 更多工作

在 Python 2 中尝试同样的事情会导致问题:

Python 2 - more work

Trying the same thing in Python 2 causes problems:

class Vehicle:
    def __init__(self):
        print('Vehicle __init__() called')

class Car(Vehicle):
    def __init__(self):
        super().__init__()


car = Car()

抛出这个异常:

Traceback (most recent call last):
...
TypeError: super() takes at least 1 argument (0 given)

我们需要提供自己的类作为第一个和 self 作为 super() 的第二个参数:

We need to supply the own class as first and and self as second argument to super():

class Vehicle:
    def __init__(self):
        print('Vehicle __init__() called')

class Car(Vehicle):
    def __init__(self):
        super(Car, self).__init__()

car = Car()

但这还不够:

Traceback (most recent call last):
...
TypeError: must be type, not classobj

class Vehicle: 创建一个旧式的类.Vehicle 必须从 object 继承以获得一个与 super() 一起使用的新式类:

class Vehicle: creates an old-style class. Vehicle has to inherit from object to get a new-style class that works with super():

class Vehicle(object):
    def __init__(self):
        print('Vehicle __init__() called')

class Car(Vehicle):
    def __init__(self):
        super(Car, self).__init__()

car = Car()

印刷品:

Vehicle __init__() called

super() 在 Python 2 中没有参数

必须一直记住这两个论点有点烦人.幸运的是，有一个解决方案.强烈推荐的库 Python-Future 允许您在 Python 中不带参数地使用 super()2:

super() without arguments in Python 2

Having to remember these two arguments all the time is kind of annoying. Fortunately, there is a solution. The highly recommended library Python-Future allows you to use super() without arguments in Python 2:

from builtins import object, super # from Python-Future

class Vehicle(object):
    def __init__(self):
        print('Vehicle __init__() called')

class Car(Vehicle):
    def __init__(self):
        super().__init__()

car = Car()

印刷品:

Vehicle __init__() called

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