• 問(wèn)題背景: 源于公司的原來(lái)的代碼是python2開(kāi)發(fā)的，后來(lái)改為python3開(kāi)發(fā)，設(shè)計(jì)到的property的用法有點(diǎn)不一樣
• 直接上代碼

公司原來(lái)的python2的代碼

          
            class LineItem:

    def __init__(self, description, weight, price):
        self.description = description
        self.__weight = weight
        self.price = price

    @property
    def weight(self):
        return self.__weight

    @weight.setter
    def set_weight(self, value):
        if value > 0:
            self.__weight = value
        else:
            raise ValueError('weight must be > 0')
          
        

運(yùn)行代碼

          
            In [2]: l = LineItem('a', 3, 6)

In [3]: l.weight
Out[3]: 3

In [4]: l.weight = 5

In [5]: l.weight
Out[5]: 5
          
        

這個(gè)代碼在python2下面執(zhí)行沒(méi)有問(wèn)題，但是在python3下面執(zhí)行，會(huì)報(bào)錯(cuò)，在執(zhí)行 In [4]: l.weight = 5 的時(shí)候報(bào)錯(cuò)

          
            In [4]: l.weight = 5
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

            
               in 
              
                
----> 1 l.weight = 5

AttributeError: can't set attribute
              
            
          
        

• 解決方法

按理說(shuō)，上面的那種寫法不是很規(guī)范，無(wú)論是在python2還是python3的文檔實(shí)例里面都不是這么寫的，所以為了簡(jiǎn)便和不出錯(cuò)，我們統(tǒng)一使用下面的這種寫法

          
            class LineItem:

    def __init__(self, description, weight, price):
        self.description = description
        self.__weight = weight
        self.price = price

    @property
    def weight(self):
        return self.__weight

    @weight.setter
    def weight(self, value):
        if value > 0:
            self.__weight = value
        else:
            raise ValueError('weight must be > 0')
          
        

主要區(qū)別在于這一行 def weight(self, value):