Python：如何正确使用带有装饰器的方法

Question

我有一个Message 类，我想设置它的有效负载。但是，我无法弄清楚如何使用正确的方法来做到这一点。这是Message 类在源代码中的样子（删除了不相关的部分）：

class Message(object):
    def __init__(self):
        self._type = None
        self._mid = None
        self._token = None
        self._options = []
        self._payload = None
        self._destination = None
        self._source = None
        self._code = None
        self._acknowledged = None
        self._rejected = None
        self._timeouted = None
        self._cancelled = None
        self._duplicated = None
        self._timestamp = None
        self._version = 1

    @property
    def payload(self):
        """
        Return the payload.

        :return: the payload
        """
        return self._payload

    @payload.setter
    def payload(self, value):
        """
        Sets the payload of the message and eventually the Content-Type

        :param value: the payload
        """
        if isinstance(value, tuple):
            content_type, payload = value
            self.content_type = content_type
            self._payload = payload
        else:
            self._payload = value

如果我尝试使用messageObject.payload("Hello World") 设置有效负载，则会收到错误：TypeError: 'NoneType' object is not callable。

设置有效载荷的正确方法是什么？

Answer 1

当你使用property decorator时，payload不再作为方法使用，它变成了属性，表示装饰器名称，用法如下：

message_object.payload = "Hello World" # set the payload property
message_object.payload # get the payload property