zmievsa / cached_classproperty

cached_property for class properties instead of instance properties

Hi there, my name is Stanislav Zmiev 👋

• I am a Platform Engineer with an extensive experience in devtools and backend Development
• I have done a fair share of frontend, mobile, DevOps, and lower level stuff in my spare time
• I have built numerous open source projects over the years, most of which can be found on my GitHub page
• My passion is creating and combining development tools to provide programmers with the best possible support while coding. To increase value without needing to increase the team size
• In my spare time, I contribute to open source and participate in developer meetups and conferences. Over the years I have contributed code to:
  • CPython
  • typeshed
  • tortoise-orm
  • ideas
  • pygount
  • inflect

... any many smaller projects!

cached_classproperty's Issues

Support for Python 3.8 and 3.9

cached_classproperty claims to support Python >= 3.8 but works only on Python >= 3.10 because of the typing union operator used ("|"). The operator should be replaced with Union/Optional to support versions before 3.10.

Related to zmievsa/pydantic-duality#8.

`cached_classproperty` can result in surprising result in inherited classes

Describe the bug
cached_classproperty can result in surprising result in inherited classes

To Reproduce

from cached_classproperty import cached_classproperty

class Superclass:
    @classmethod
    def my_classmethod(cls):
        return ('Superclass.x',)

    @cached_classproperty
    def my_cached_classproperty(cls):
        return cls.my_classmethod()

class Subclass1(Superclass):
    @classmethod
    def my_classmethod(cls):
        return (*super().my_classmethod(), 'Subclass1.x',)

class Subclass2(Superclass):
    @classmethod
    def my_classmethod(cls):
        return (*super().my_classmethod(), 'Subclass2.x',)

class Finalclass(Subclass1, Subclass2):
    @classmethod
    def my_classmethod(cls):
        return (*super().my_classmethod(), 'Finalclass.x',)


print("Subclass2.my_cached_classproperty", Subclass2.my_cached_classproperty)
print("Superclass.my_cached_classproperty", Superclass.my_cached_classproperty)
print("Finalclass.my_cached_classproperty", Finalclass.my_cached_classproperty)
print("Subclass1.my_cached_classproperty", Subclass1.my_cached_classproperty)

print("Superclass.my_classmethod()", Superclass.my_classmethod())
print("Finalclass.my_classmethod()", Finalclass.my_classmethod())
print("Subclass1.my_classmethod()", Subclass1.my_classmethod())
print("Subclass2.my_classmethod()", Subclass2.my_classmethod())

Output:

Subclass2.my_cached_classproperty ('Superclass.x', 'Subclass2.x')
Superclass.my_cached_classproperty ('Superclass.x',)
Finalclass.my_cached_classproperty ('Superclass.x', 'Subclass2.x')
Subclass1.my_cached_classproperty ('Superclass.x',)
Superclass.my_classmethod() ('Superclass.x',)
Finalclass.my_classmethod() ('Superclass.x', 'Subclass2.x', 'Subclass1.x', 'Finalclass.x')
Subclass1.my_classmethod() ('Superclass.x', 'Subclass1.x')
Subclass2.my_classmethod() ('Superclass.x', 'Subclass2.x')

Expected behavior
my_cached_classproperty should return the result same as my_classmethod()

Additional context

$ python --version
Python 3.10.12