类的装饰器

def demo(obj):
    print('===================')
    obj.x = 1
    obj.y = 2
    obj.z = 3
    return obj

@demo
class Foo:
    pass

f1 = Foo()
print(Foo.__dict__)
输出：
===================
{'__module__': '__main__', '__dict__': <attribute '__dict__' of 'Foo' objects>, '__weakref__': <attribute '__weakref__' of 'Foo' objects>, '__doc__': None, 'x': 1, 'y': 2, 'z': 3}

一切皆对象，函数和类都是对象    例如：

def demo(obj):
    print('===================')
    obj.x = 1
    obj.y = 2
    obj.z = 3
    return obj
@demo
def test():
    print('这是个测试函数')
test()
print(test.__dict__)
输出：
===================
这是个测试函数
{'x': 1, 'y': 2, 'z': 3}

def test(**kwargs):
    def wrapper(obj):
        for key, val in kwargs.items():
            setattr(obj, key, val)
        return obj

    return wrapper


@test(a=1, b=2)  # @wrapper
class Foo:
    def __init__(self, name):
        self.name = name


print(Foo.__dict__)
输出：
{'__module__': '__main__', '__init__': <function Foo.__init__ at 0x00000000024C3280>, '__dict__': <attribute '__dict__' of 'Foo' objects>, '__weakref__': <attribute '__weakref__' of 'Foo' objects>, '__doc__': None, 'a': 1, 'b': 2}