Strange behavior with prints inside lru_cached properties

[Heshy Roskes]

class A:
  def __init__(self):
    self.b = 3
  @methodtools.lru_cache()
  @property
  def a(self):
    print("here")
    print("here", self.b)
    return self.b

When I run this code, I get the printout here. The print statement seems to run at the time of class creation.

If I then do

a = A()
a.a

I get

here
here 3

as expected.

[Jeong, YunWon]

This is weird, but I am not sure methodtools can avoid that behavior. It seems like a side effect from decorator detection.

I want to recommend cached_property for this use case.
Official: https://docs.python.org/dev/library/functools.html?highlight=s#functools.cached_property
For python < 3.8: https://pypi.org/search/?q=cached+property

[Jeong, YunWon]

I decided to add special handling for built-in property, thank you!