I have the following scenario:
class A:
b = 1
pass
x = A()
y = A()
Can I change this class so that x.b = 2 is equivalent to A.b = 2, I mean, when a change the static variable for one instance it´s changed for all instances?
Edit: I want to be able to work with multiple different instances of this class.
You can, but it's kind of ugly:
class A:
b = 1
def __setattr__(self, name, value):
if name == "b":
setattr(A, "b", value)
else:
super().__setattr__(name, value)
This would work as expected now:
>>> a = A()
>>> a.b = 3
>>> A.b
3
>>> A.b = 5
>>> a.b
5
The real question is: Why would you want that?
If you're going to use this often, it might be nice to write a decorator for it:
def sharedclassvar(variable):
def __setattr__(self, name, value):
if name in self.__class__._sharedclassvars:
setattr(self.__class__, name, value)
elif hasattr(self.__class__, "__oldsetattr__"):
self.__class__.__oldsetattr__(self, name, value)
else:
super().__setattr__(name, value)
def decorator(cls):
if not hasattr(cls, "_sharedclassvars"):
cls._sharedclassvars = []
if hasattr(cls, "__setattr__"):
cls.__oldsetattr__ = getattr(cls, "__setattr__")
cls.__setattr__ = __setattr__
cls._sharedclassvars.append(variable)
return cls
return decorator
You can then define such a class like this:
@sharedclassvar("b")
class A:
b = 1
