Python中的多态 [英] Polymorphism in Python

问题描述

class File(object):
    def __init__(self, filename):
        if os.path.isfile(filename):
            self.filename = filename
            self.file = open(filename, 'rb')
            self.__read()
        else:
            raise Exception('...')

    def __read(self):
        raise NotImplementedError('Abstract method')

class FileA(File):
    def __read(self):
        pass

file = FileA('myfile.a')

# NotImplementedError: Abstract method

我的问题:怎么了?如何将我的代码固定到FileA，请使用FileA.__read()而不是File.__read()来读取文件? :S

My question: what's wrong? How I can fix my code to FileA use FileA.__read() to read the file instead of File.__read()? :S

谢谢.

推荐答案

使用双下划线作为前缀的属性不会使该属性变为私有，只会使多态性成为不可能，因为该属性名称会被 current所混淆类名.改为将其更改为单个下划线前缀.

Prefixing an attribute with double underscores doesn't make the attribute private, it simply makes polymorphism impossible because the attribute name gets mangled with the current class name. Change it to a single underscore prefix instead.

这篇关于Python中的多态的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！