对def __init__内部的__init__方法感到困惑 [英] confused about __init__ method inside of def __init__

问题描述

在以下代码中:

import tkinter as tk

    class CardShuffling(tk.Tk):
        background_colour = '#D3D3D3'
        deck_size = 52

        def __init__(self):
            tk.Tk.__init__(self) # What does this do?

我对最后一行的目的感到困惑.CardShuffling实例从tk.Tk继承，不是最后一行只是重复CardShuffling(tk.Tk)已经处理的内容?

I am confused about the purpose of the last line.. an instance of CardShuffling inherits from tk.Tk, doesn't the last line just repeat what is already taken care of by CardShuffling(tk.Tk) ??

推荐答案

CardShuffling(tk.Tk)仅使类CardShuffling成为tk.Tk的子级.您的新类继承了该类的所有方法.

CardShuffling(tk.Tk) only makes the class CardShuffling a child of tk.Tk. your new class inherits all the methods of this class.

但是，如果您创建一个新对象，则仍然必须调用该基类的构造函数(以新对象作为参数).想象在父类的构造函数中有一行self.a = 0.初始化新实例时，您的子类必须运行此行； CardShuffling(tk.Tk)不能为您做到这一点；您需要运行父类的__init__.

but if you create a new object you still have to call the constructor of that base class (with the new object as argument). imagine there is a line self.a = 0 in the constructor of the parent class. your child class has to run this line when you initialize a new instance; CardShuffling(tk.Tk) can not do that for you; you need to run __init__ of the parent class.

在python 3中执行此操作的通常方法是

the usual way to do that in python 3 is

def __init__(self):
    super().__init__()

在这种情况下与

def __init__(self):
    tk.Tk.__init__(self)

也许关于继承的文章会有所帮助，甚至还有书籍章节.

maybe this article on inheritance helps and there is even a book chapter freely available.

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