如何有效地检测Python 3中变量的变化？

class MyClass:
    def __init__(self):
        self._my_variable = None

    @property
    def my_variable(self):
        return self._my_variable

    @my_variable.setter
    def my_variable(self, value):
        if self._my_variable != value:
            print("Variable changed!")
        self._my_variable = value

obj = MyClass()
obj.my_variable = 10  # 输出 "Variable changed!"

from observable import Observable

class MyClass(Observable):
    def __init__(self):
        super().__init__()
        self._my_variable = None

    @property
    def my_variable(self):
        return self._my_variable

    @my_variable.setter
    def my_variable(self, value):
        if self._my_variable != value:
            self.notify_observers("Variable changed!")
        self._my_variable = value

class Observer:
    def update(self, message):
        print(message)

obj = MyClass()
obj.add_observer(Observer())
obj.my_variable = 10  # 输出 "Variable changed!"

class MyClass:
    def __init__(self):
        self._my_variable = None

    def __setattr__(self, name, value):
        if name == "my_variable" and self._my_variable != value:
            print("Variable changed!")
        super().__setattr__(name, value)

obj = MyClass()
obj.my_variable = 10  # 输出 "Variable changed!"