字符串的ABC吗？ [英] ABC for String?

问题描述

我最近在集合中发现了抽象基类（ABC），并且喜欢它们清晰，系统的方法和Mixins。现在，我也想创建海关字符串（*），但找不到字符串的ABC。

I recently discovered abstract base classes (ABCs) in collections and like their clear, systematic approach and Mixins. Now I also want to create customs strings (*), but I couldn't find an ABC for strings.

有UserString，但是不鼓励UserDict！从str本身派生出来就不会有Mixins吗？您如何在覆盖的方法中访问字符串的数据部分？

There is UserString, but UserDict was discouraged!? Deriving from str itself would have no Mixins? How would you access the "data" part of the string in overridden methods?

在某个地方，我看到了从Sequence和Hashable派生的建议，但是后来我写不出来如果在my_string中进行测试：？！

Somewhere I saw the suggestions to derive from Sequence and Hashable, but then I couldn't write if 'test' in my_string:?!

您推荐哪种方法？

（*）原因是：
-以内部定义的方式编写按顺序排列的字符串
-生成字符串（作为枚举的一部分），与枚举范围之外的值

(*) The reasons are: - write strings that order in an internally defined way - make string (as part of an enumeration), that throw errors when comparing to values outside the enumeration scope

推荐答案

这是史蒂文答案的一个愚蠢但快速的示例。它是在Python 3中实现的（即Unicode字符串，不带参数的 super 和 __ getitem __ 切片）：

Here's a silly, but quick, example of Steven's answer. It's implemented in Python 3 (i.e. Unicode strings, super without arguments, and __getitem__ slices):

class MultiStr(str):
    def __new__(cls, string, multiplier=1, **kwds):
        self = super().__new__(cls, string, **kwds)
        self.multiplier = multiplier
        return self

    def __getitem__(self, index):
        item = super().__getitem__(index)
        return item * self.multiplier

>>> s = MultiStr(b'spam', multiplier=3, encoding='ascii')
>>> s[0]
'sss'
>>> s[:2]
'spspsp'
>>> s[:]
'spamspamspam'

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