如何返回类中的所有数据

class MyClass:
    def __init__(self, data):
        self.data = data

    def get_data(self):
        return self.data

obj = MyClass("Hello World")
print(obj.get_data())  # 输出：Hello World

class MyClass:
    def __init__(self, data):
        self.data = data

    def __str__(self):
        return self.data

obj = MyClass("Hello World")
print(obj)  # 输出：Hello World

class MyClass:
    def __init__(self, data):
        self.data = data

obj = MyClass("Hello World")
print(obj.__dict__)  # 输出：{'data': 'Hello World'}

class MyClass:
    def __init__(self, data):
        self.data = data

    def my_method(self):
        pass

obj = MyClass("Hello World")
print(dir(obj))  # 输出：['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'data', 'my_method']