将对象转换为字典键

发布于 2025-01-23 18:54:18 字数 452 浏览 0 评论 0原文

我想知道是否有一种简单的方法可以在字典中以一个值进行多个键。我想实现的一个示例如下：

class test:
    key="test_key"
    
    def __str__(self):
        return self.key

tester = test()

dictionary = {}
dictionary[tester] = 1

print(dictionary[tester])
print(dictionary["test_key"])

输出在哪里：

>>> 1
>>> 1

我要寻找的是一种将对象自动转换为字符串之前的方法。这可能吗？

原文

I was wondering if there is an easy way to essentially have multiple keys in a dictionary for one value. An example of what I would like to achieve is as following:

class test:
    key="test_key"
    
    def __str__(self):
        return self.key

tester = test()

dictionary = {}
dictionary[tester] = 1

print(dictionary[tester])
print(dictionary["test_key"])

where the output would be:

>>> 1
>>> 1

What I'm looking for is a way to automatically convert the object to a string before its used as a key. Is this possible?

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子栖 2025-01-30 18:54:18

就个人而言，我认为最好将对象明确地施放到字符串上，例如

dictionary[str(tester)] = 1

，如果您确实 真的确保要执行此操作，定义__哈希__和__ eq __ dunder方法。无需创建新的数据结构或更改类定义之外的现有代码：

class test:
    key="test_key"
    
    def __hash__(self):
        return hash(self.key)
        
    def __eq__(self, other):
        if isinstance(other, str):
            return self.key == other
        return self.key == other.key
    
    def __str__(self):
        return self.key

这将输出：

1
1

Personally, I think it's better to explicitly cast the object to a string, e.g.

dictionary[str(tester)] = 1

That being said, if you're really really REALLY sure you want to do this, define the __hash__ and __eq__ dunder methods. No need to create a new data structure or change the existing code outside of the class definition:

class test:
    key="test_key"
    
    def __hash__(self):
        return hash(self.key)
        
    def __eq__(self, other):
        if isinstance(other, str):
            return self.key == other
        return self.key == other.key
    
    def __str__(self):
        return self.key

This will output:

1
1

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挽清梦 2025-01-30 18:54:18

几乎可以肯定的是，您不应该这样做。只需使用字典[str（tester）]。它更可读，令人惊讶，只有五个字符要写。

但是，如果您坚持认为，这是我能想到的最好的

class StrKeyedDict(dict):
    def __getitem__(self, key):
        return super().__getitem__(str(key))
    def __setitem__(self, key, value):
        super().__setitem__(str(key), value)
    # ... do all the other methods that mess with the key

class Test:
    key="test_key"

    def __str__(self):
        return self.key

tester = Test()
dictionary = StrKeyedDict()
dictionary[tester] = 1
print(dictionary["test_key"])
# => 1

It is almost certain you should not do this; just use dictionary[str(tester)]. It is more readable, less surprises, only five characters more to write.

If you insist though, this is the best I can think of

class StrKeyedDict(dict):
    def __getitem__(self, key):
        return super().__getitem__(str(key))
    def __setitem__(self, key, value):
        super().__setitem__(str(key), value)
    # ... do all the other methods that mess with the key

class Test:
    key="test_key"

    def __str__(self):
        return self.key

tester = Test()
dictionary = StrKeyedDict()
dictionary[tester] = 1
print(dictionary["test_key"])
# => 1

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