Python中的多态性

Polymorphism in Python(Python中的多态性)

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?如何将我的代码修复到 FileA 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

提前谢谢你.

推荐答案

用双下划线前缀属性不会使属性私有，它只会使多态性变得不可能，因为属性名称与 当前 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中的多态性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编程学习网！