I'm looking for a way to cache properties of an object. In my case, I suppose the object can change over the time, so the memoized value for the property should be flushable. In pure python, I want to have a behaviour like:

```py
class Foo:
  def __init__(self, text: str):
    self._text  = text
    self._bar = None

  def flush(self):
     self._bar = None

  def update_text(self, text: str):
     self._text = text 
     self.flush()

  @property
  def bar(self):
    if self._bar is None:
      print('Computing bar...')
      self._bar = f'Computation with "{self._text}".'
    return self._bar

foo1 = Foo('Dog')
foo2 = Foo('Fish')

print(foo1.bar)
# Computing bar...
# Computation with "Dog".

print(foo1.bar)
# Computation with "Dog".

print(foo2.bar)
# Computing bar...
# Computation with "Fish".

print(foo2.bar)
# Computation with "Fish".

foo1.update_text('Cat')

print(foo1.bar)
# Computing bar...
# Computation with "Cat".

print(foo1.bar)
# Computation with "Cat".

print(foo2.bar)
# Computation with "Fish".

```

Then, as you can see, I want to cache the `Foo.bar` property. My approach was to define a private property initialised as `None` and then assigned and flushed to obtain a memoized behaviour. 

**Now, my question is if there is some method, library, approach or technique to obtain this behaviour without the need to have a private property (imagine you have tends of memoizable properties in the class).** 

I was reading about the `@lru_cache()` decorator (and the newest `@cached_property`) from the Standard Library (<https://docs.python.org/3/library/functools.html>), but I realised that the `cache_clear()` method removes the memoized values for all the instances of the class.

I was thinking that one possible solution could be to use immutable objects, but that solution is not as I want, because probably there will be situations in which I only want to flush one of the properties memoization.