Python: @staticmethod with @property

Question

I want

Stats.singleton.twitter_count += 1

and I thought I could do

class Stats:
    singleton_object = None

    @property
    @staticmethod
    def singleton():
        if Stats.singleton_object:
            return Stats.singleton_object
        Stats.singleton_object = Stats()
        return Stats.singleton()

But it throws an exception:

>>> Stats.singleton.a = "b"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'property' object has only read-only attributes (assign to .a)

Answer 1

Static methods don't make sense in Python. That's because they do nothing that class methods can't, and are class methods much easier to extend in the future (when multiple class methods use each other etc).

What you need is simply a class method property.

I have a class method property from my code here. It is only read-only, that was all I needed (so the rest is an exercise to the reader):

class ClassProperty (property):
    """Subclass property to make classmethod properties possible"""
    def __get__(self, cls, owner):
        return self.fget.__get__(None, owner)()

# how I would use it
class Stats:
    singleton_object = None
    @ClassProperty
    @classmethod
    def singleton(cls):
        if cls.singleton_object is None:
            cls.singleton_object = cls()
        return cls.singleton_object

Answer 2

Singletons are pointless in python.

class A:
  class_var = object()

# two objects
a, b = A(), A()

# same var everywhere
assert a.class_var is b.class_var is A.class_var

Python's ints are differnt from simple objects, so it's not always that simple . But for your purposes, this seems to be enough:

class Stats:
    twitter_count = 0

Stats.twitter_count +=1
Stats.twitter_count +=1
assert Stats.twitter_count == 2