如何确保子类具有与基督平均相同的初始分散器？

发布于 2025-01-24 19:21:33 字数 755 浏览 2 评论 0 原文

这就是我的代码的样子：

import uuid

class UniversalID(str):
    def __init__(self, val:str):
        super().__init__()
        try:
            uuid.UUID(hex=val)
            self=val
        except ValueError as inv_str:
            logging.error(msg=f'Invalid id queried {val}')
            raise inv_str

sample= uuid.uuid1().hex
isinstance(UniversalID(sample), str) # Shows true, as expected

但是不确定这是否是正确的方法，因为可能还有其他我不照顾的 str initialiser的参数。

这个问题可以推广到，如果我想在子类中使用一些验证检查的 __ INT __ 方法相同的论点和处理方式相同？更糟糕的是，我是否必须复制粘贴代码？

原文

Basically, I am trying to define a subclass of string which conforms with the RFC UUID scheme. An object of this class can only exist if it conforms to the 8-4-4-4-12 hex string, else does not. So I need to check it during initialisation, but not sure how to account for all possible initialisation arguments of str.

This is how my code looks like:

import uuid

class UniversalID(str):
    def __init__(self, val:str):
        super().__init__()
        try:
            uuid.UUID(hex=val)
            self=val
        except ValueError as inv_str:
            logging.error(msg=f'Invalid id queried {val}')
            raise inv_str

sample= uuid.uuid1().hex
isinstance(UniversalID(sample), str) # Shows true, as expected

But not sure if this is the right approach, as there may be other arguments of str initialiser that I am not taking care of.

The question can be generalised to, if I want to modify the __init__ method with some validation check in the subclass, do I need to have total access to the initialiser in the base class, to make sure it accepts the same arguments and processes the same way? Worse still, do I have to, like, copy paste the code?

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梨涡 2025-01-31 19:21:34

您可能需要创建一个从 uuid.uuid 继承的实例，并在将其传递给您的构造函数中，然后将其传递给您的构造函数。

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沫离伤花 2025-01-31 19:21:33

正如我在评论中所说的那样，您必须在其 __新__（）方法中设置不变类型（如字符串）的价值。我找不到适合您的规范来源或示例 - 我从很久以前读过的一些书中知道这一点，所以决定为您组成一个（基于您的代码）：

import logging
import uuid


class UniversalID(str):
    # You don't really need to define this, because it's what would happen anyway.
    def __new__(cls, *args, **kwargs):
        return super().__new__(cls, *args, **kwargs)

    def __init__(self, *args, **kwargs):
        try:
            uuid.UUID(hex=self)
        except ValueError as inv_str:
            logging.error(msg=f'Invalid id queried {self}')
            raise inv_str


if __name__ == '__main__':

    sample1 = uuid.uuid1().hex
    try:
        isinstance(UniversalID(sample1), str)
    except ValueError as exc:
        print(f'ERROR: {exc} {sample1=!r}')
    else:
        print(f'{sample1=!r} is a valid hex uuid.')

    print()
    sample2 = 'not a hex uuid'
    try:
        isinstance(UniversalID(sample2), str)
    except ValueError as exc:
        print(f'ERROR: {exc} {sample2=!r}')
    else:
        print(f'{sample2=!r} is a valid hex uuid.')

As I said in a comment you have to set the value of immutable types, like strings, in their __new__() method. I couldn't find a canonical source or example for you — I know about it from some books I read long ago, so decided just to make up one for you (based on your code):

import logging
import uuid


class UniversalID(str):
    # You don't really need to define this, because it's what would happen anyway.
    def __new__(cls, *args, **kwargs):
        return super().__new__(cls, *args, **kwargs)

    def __init__(self, *args, **kwargs):
        try:
            uuid.UUID(hex=self)
        except ValueError as inv_str:
            logging.error(msg=f'Invalid id queried {self}')
            raise inv_str


if __name__ == '__main__':

    sample1 = uuid.uuid1().hex
    try:
        isinstance(UniversalID(sample1), str)
    except ValueError as exc:
        print(f'ERROR: {exc} {sample1=!r}')
    else:
        print(f'{sample1=!r} is a valid hex uuid.')

    print()
    sample2 = 'not a hex uuid'
    try:
        isinstance(UniversalID(sample2), str)
    except ValueError as exc:
        print(f'ERROR: {exc} {sample2=!r}')
    else:
        print(f'{sample2=!r} is a valid hex uuid.')

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