Python 3 中 __total__ dunder 属性的含义是什么

Python 3 中的 __total__ dunder 属性是一个用于控制类的属性和方法是否可以被子类继承的特殊属性。当在一个类中定义 __total__ 属性并设置为 True 时，子类可以继承父类的所有属性和方法。但当 __total__ 属性设置为 False 时，子类只能继承父类中的非 __total__ 属性和方法。

python
class Parent:
    __total__ = True
    def __init__(self, name):
        self.name = name
    def say_hello(self):
        print("Hello, I am", self.name)
    def parent_method(self):
        print("This is a parent method")
class Child(Parent):
    def child_method(self):
        print("This is a child method")
parent = Parent("Parent")
child = Child("Child")
parent.say_hello()  # 输出：Hello, I am Parent
child.say_hello()  # 输出：Hello, I am Child
parent.parent_method()  # 输出：This is a parent method
child.parent_method()  # 输出：This is a parent method
child.child_method()  # 输出：This is a child method

python
class Parent:
    __total__ = False
    def __init__(self, name):
        self.name = name
    def say_hello(self):
        print("Hello, I am", self.name)
    def parent_method(self):
        print("This is a parent method")
class Child(Parent):
    def child_method(self):
        print("This is a child method")
parent = Parent("Parent")
child = Child("Child")
parent.say_hello()  # 输出：Hello, I am Parent
child.say_hello()  # 输出：Hello, I am Child
parent.parent_method()  # 输出：This is a parent method
child.parent_method()  # 报错：AttributeError: 'Child' object has no attribute 'parent_method'
child.child_method()  # 输出：This is a child method