继承和覆盖__init__在python中 [英] Inheritance and Overriding __init__ in python

问题描述

我正在阅读深入Python"，并且在有关类的章节中给出了以下示例:

I was reading 'Dive Into Python' and in the chapter on classes it gives this example:

class FileInfo(UserDict):
    "store file metadata"
    def __init__(self, filename=None):
        UserDict.__init__(self)
        self["name"] = filename

作者然后说，如果要覆盖__init__方法，则必须使用正确的参数显式调用父__init__.

The author then says that if you want to override the __init__ method, you must explicitly call the parent __init__ with the correct parameters.

1. 如果该FileInfo类具有多个祖先类怎么办?
   • 是否必须显式调用所有祖先类的__init__方法?

1. What if that FileInfo class had more than one ancestor class?
   • Do I have to explicitly call all of the ancestor classes' __init__ methods?

推荐答案

关于子类-超类调用，本书有些过时了.在子类化内置类方面也有些过时.

The book is a bit dated with respect to subclass-superclass calling. It's also a little dated with respect to subclassing built-in classes.

如今看起来像这样:

class FileInfo(dict):
    """store file metadata"""
    def __init__(self, filename=None):
        super(FileInfo, self).__init__()
        self["name"] = filename

请注意以下几点:

1. 我们可以直接对内置类进行子类化，例如dict，list，tuple等.

super函数负责跟踪此类的超类并在其中适当地调用函数.

The super function handles tracking down this class's superclasses and calling functions in them appropriately.

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