How do I clear the cache from @cached_property decorator?

Question

I have an function called "value" that makes heavy calculation...

The result of the function is always the same if the dataset is not changed for the identifier.

Once the dataset is changed for some identifier, I want to clear the cache, and let the function calculate it again.

You can better understand me by looking at this code:

from functools import cached_property


class Test:
    identifiers = {}
    dataset = an empty object of dataset type

    def __init__(self, identifier, ...)
        self.identifier = identifier
        ...
        Test.identifiers[identifier] = self

    ...

    @cached_property
    def value(self):
        result = None
        # heavy calculate based on dataset
        return result

    @classmethod
    def get(cls, identifier):
        if identifier in cls.identifiers:
            return cls.identifiers[identifier]
        else:
            return cls(identifier, ...)

    @classmethod
    def update(cls, dataset):
        for block in dataset:
            # assume there is block['identifier'] in each block
            # here i want to clear the cache of value() function
            instance = cls.get(block['identifier'])
            # clear @cached_property of instance
            cls.dataset.append(block)

Answer 1

As you can read in the CPython source, the value for a cached_property in Python 3.8 is stored in an instance variable of the same name. This is not documented, so it may be an implementation detail that you should not rely upon.

But if you just want to get it done without regards to compatibility, you can remove the cache with del instance.value. And who knows, maybe the current behavior will be documented in the future, so it will be safe to use it in any version or interpreter implementation.