（1）私有属性

class MyClass:
    attr1 = 'attr1'  # 共有属性
    _attr2 = '_attr2'  # 私有属性，可直接访问
    __attr3 = '__attr3'  # 私有属性，改变了属性名：_MyClass__attr3


m1 = MyClass()
print(m1.attr1)
print(MyClass.attr1)

print(m1._attr2)
print(MyClass._attr2)

print(m1._MyClass__attr3)
print(MyClass._MyClass__attr3)
print(MyClass.__dict__)
m1.att = 'gaga'  # 可动态添加属性

输出：

attr1
attr1
_attr2
_attr2
__attr3
__attr3
{'__module__': '__main__', 'attr1': 'attr1', '_attr2': '_attr2', '_MyClass__attr3': '__attr3', '__dict__': <attribute '__dict__' of 'MyClass' objects>, '__weakref__': <attribute '__weakref__' of 'MyClass' objects>, '__doc__': None}

（2）__slots__ 和 __dict__

class MyClass2:
    __slots__ = ['name']


m2 = MyClass2()
m2.name = 'haha'
# m2.cc = 'hh'   # AttributeError: 'MyClass2' object has no attribute 'cc'；只能添加slots里面声明的属性
print(m2.name)
print(MyClass2.__dict__)

输出：

haha
{'__module__': '__main__', '__slots__': ['name'], 'name': <member 'name' of 'MyClass2' objects>, '__doc__': None}